SMTP Error Code Tables

Code

Error Message

Meaning

Solution

Glossary

400

from parameter is missing

The sender's email address is not provided

Include the sender's email in the 'from' parameter

'from' parameter: Sender's email address

400

to parameter is missing

The receiver's email address is not provided

Include the receiver's email in the 'to' parameter

'to' parameter: Receiver's email address

400

message parameter is missing

The email body is not provided

Include the email body in the 'message' parameter

'message' parameter: Email body

400

‘message’ parameter is not a file

The 'message' parameter is expected to be a file but isn't

Provide the message as a file

'message' parameter: Email body, in this case expected as a file

400

Need at least one of ‘text’ or ‘html’ parameters specified

Neither plain text nor HTML versions of the email are provided

Include at least one of the 'text' or 'html' parameters

'text'/'html' parameters: Plain text/HTML versions of the email

400

Only one parameters ‘html’ or ‘template’ is allowed

Both 'html' and 'template' parameters are provided, but only one is allowed

Provide either the 'html' or 'template' parameter, not both

'html'/'template' parameters: HTML version of the email / Template for the email

400

Send options (parameters starting with o:, h:, or v:) are limited to 16 kB total

The send options provided exceed the 16 kB limit

Reduce the size of send options to less than 16 kB

'o:', 'h:', 'v:' parameters: Send options for the email

400

Too many recipients; max is 1000

The email is addressed to more than 1000 recipients

Limit the number of recipients to 1000 or less

Recipients: The individuals or groups receiving the email

400

Header name must be pure ASCII: <header-name>

The header name contains non-ASCII characters

Use only ASCII characters in the header name

ASCII: American Standard Code for Information Interchange, a character encoding standard

400

<invalid-date> is not an RFC-2822 compliant date

The provided date is not compliant with RFC-2822

Ensure the date is formatted according to RFC-2822 standards

RFC-2822: Internet Message Format specification

400

to parameter is not a valid address. please check documentation

The receiver's email address is invalid

Check and correct the format of the receiver's email address

'to' parameter: Receiver's email address

400

Invalid request content type. Expecting ‘multipart/form-data’ but got ‘application/x-www-form-urlencoded’

The content type of the request is not what is expected

Change the request content type to 'multipart/form-data'

'multipart/form-data': A type of HTTP request commonly used for file uploads

400

malformed multipart/form-data request

The 'multipart/form-data' request is formatted incorrectly

Correct the format of the 'multipart/form-data' request

'multipart/form-data': A type of HTTP request commonly used for file uploads

400

unable to parse request: invalid URL escape

The URL in the request contains invalid escape charactes

Correct the escape charactes in the URL

URL escape characters: Characters used in a URL to represent certain other charactes

400

unable to parse request: unexpected EOF

The request ends unexpectedly

Check the request for missing information or incorrect

formatting

EOF: End of File, in this case referring to the end of the request

400

<time> invalid 24 hour time(value of ‘o:time-zone-localize’)

The time provided is not in a valid 24-hour format

Ensure the time is in a valid 24-hour format

'o:time-zone-localize': A parameter for setting the time zone

400

<time> is not a valid time to send (value of ‘o:time-zone-localize’)

The specified time is not a valid time to send the email

Choose a different, valid time to send the email

'o:time-zone-localize': A parameter for setting the time zone

400

invalid delivery time format

The format of the delivery time is invalid

Correct the format of the delivery time

Delivery time: The time when the email should be delivered

400

to parameter is not a valid address. please check documentation

The receiver's email address is invalid

Check and correct the format of the receiver's email address

'to' parameter: Receiver's email address

400

from parameter is not a valid address. please check documentation

The sender's email address is invalid

Check and correct the format of the sender's email address

'from' parameter: Sender's email address

400

cc parameter is not a valid address. please check documentation

The CC email address is invalid

Check and correct the format of the CC email address

'cc' parameter: Carbon copy email address

400

bcc parameter is not a valid address. please check documentation

The BCC email address is invalid

Check and correct the format of the BCC email address

'bcc' parameter: Blind carbon copy email address

400

‘recipient-variables’ parameter is not a valid JSON

The 'recipient-variables' parameter is not correctly formatted as JSON

Correct the format of the 'recipient-variables' parameter

'recipient-variables' parameter: Variables specific to each recipient of the email

400

Domain example.com is not allowed to send: Sandbox subdomains are for test purposes only. Please add your own domain or add the address to authorized recipients in Account Settings.

The sender's domain is a sandbox subdomain, which are for testing only

Use a non-sandbox domain, or add the recipient to the list of authorized recipients

Sandbox domain: A domain for testing purposes

400

Domain example.com is not allowed to send: Free accounts are for test purposes only. Please upgrade or add the address to authorized recipients in Account Settings.

The sender's account is a free account, which is for testing only

Upgrade to a paid account, or add the recipient to the list of authorized recipients

Free account: An account that doesn't require payment

400

Domain example.com is not allowed to send: The domain is unverified and requires DNS configuration. Log in to your control panel to view required DNS records.

The sender's domain is unverified and needs DNS configuration

Verify the domain and configure the DNS as needed

DNS: Domain Name System, a system for translating domain names to IP addresses

400

Domain example.com is not allowed to send: Please activate your Mailgun account. Check your inbox or log in to your control panel to resend the activation email.

The sender's Mailgun account is not activated

Activate the Mailgun account by following the instructions in the activation email

Mailgun: A service for sending, receiving and tracking emails

400

is not a valid secondary dkim domain name

The provided secondary DKIM domain name is invalid

Check and correct the format of the secondary DKIM domain name

DKIM: DomainKeys Identified Mail, a method for verifying the authenticity of email senders

401

Forbidden

The user does not have the necessary permissions for the request

Ensure the user has the correct permissions for the request

Forbidden: A status code indicating the user doesn't have necessary permissions

404

Domain not found: example.com

The specified domain does not exist

Use a valid, existing domain

Domain: The part of an email address after the @ symbol

403

Domain example is not allowed to send large batches yet

The specified domain is not authorized to send large batches of emails

Request permission to send large batches, or send smaller batches

Batch: A group of emails sent as part of a single operation

403

Rejected: IP <id-address> can’t be used to send the message

The IP address of the sender is not allowed to send the message

Use a different, authorized IP address to send the message

IP address: A unique identifier for devices on a network

413

request size exceeds 52.4MiB limit

The size of the request exceeds the limit of 52.4MiB

Reduce the size of the request to under 52.4MiB

MiB: Mebibyte, a unit of digital storage

429

Domain example.com is not allowed to send: request limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC

The sender's domain has exceeded the limit for sending requests

Wait until the specified time, then try sending the request again

Request limit: The maximum number of requests that can be sent in a given time period

429

Domain example.com is not allowed to send: bytes limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC

The sender's domain has exceeded the limit for sending bytes

Wait until the specified time, then try sending the request again

Bytes limit: The maximum amount of data that can be sent in a given time period

429

Domain example.com is not allowed to send: recipient limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC

The sender's domain has exceeded the limit for number of recipients

Wait until the specified time, then try sending the request again

Recipient limit: The maximum number of recipients that can be addressed in a given time period

500

Internal Server Error

There is a problem with the server

Wait and try the request again later, or contact the server administrator

Internal Server Error: A general-purpose status code indicating a problem with the server

Error Codes for Gmail / Google Workspace:

421, "4.3.0"

MeaningTemporary System Problem. Try again later

Retry sending the message later

SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages

421, "4.4.5"

The server is busy; try again later

Retry sending the message later

421, "4.7.0"

IP not in whitelist for RCPT domain, closing connection

Check if your IP address is allowed to send emails to the receiver

RCPT: SMTP command to specify the recipient of the message

421, "4.7.0"

Our system has detected an unusual rate of unsolicited mail originating from your IP address.

Review your sent emails for any potential unsolicited mail.

421, "4.7.0"

Temporary System Problem. Try again later

Retry sending the message later

421, "4.7.0"

TLS required for RCPT domain, closing connection

Make sure your system supports TLS (Transport Layer Security)

TLS: Protocol that provides communications security over a computer network

421, "4.7.0"

Try again later, closing the connection

Retry sending the message later

DoS: Denial of Service, a cyber-attack that makes a machine or network resource unavailable

450, "4.2.1"

The user you are trying to contact is receiving mail too quickly

Resend your message at a later time

450, "4.2.1"

The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered.

Resend your message at a later time.

450, "4.2.1"

Peak SMTP relay limit exceeded for customer

Try reducing the number of sent emails

SMTP relay: Process of transferring an email from one mail server to another

451, "4.3.0"

The mailMail server temporarily rejected the message

Retry sending the message later

451, "4.3.0"

Multiple destination domains per transaction is unsupported

Send your message to a single domain at a time

Domain: Part of the network address that represents a specific entity (like a company) on the internet

451, "4.4.2"

Timeout - closing connection

Retry sending the message later

451, "4.5.0"

SMTP protocol violation

Ensure that your system is correctly following the SMTP protocol

SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages

452, "4.2.2"

The email account that you tried to reach is over quota

Ask the recipient to clear their inbox

Over quota: When a user has filled their storage limit

452, "4.5.3"

Domain policy size per transaction exceeded

Try sending to the recipient in a separate transaction

452, "4.5.3"

Your message has too many recipients

Reduce the number of recipients for your message

454, "4.5.0"

SMTP protocol violation, no commands allowed to pipeline after STARTTLS.

Check your SMTP relay settings and try again.

STARTTLS: A way to take an existing insecure connection and upgrade it to a secure connection using SSL/TLS.

454, "4.7.0"

Cannot authenticate due to a temporary system problem.

Try again later. If the problem persists, contact your email provider.

Authenticate: To verify the identity of a user, device, or system.

501, "5.5.2"

Cannot decode the response.

This can be a server-side issue. Try again later or contact your service provider.

Decode: To convert from an encoded or encrypted form to plain text.

501, "5.5.4"

HELO/EHLO argument is invalid.

Check your SMTP server configuration for errors.

HELO/EHLO: SMTP commands sent by an email server to identify itself when connecting to another email server.

502, "5.5.1"

Too many unrecognized commands, goodbye.

Check your SMTP commands for any mistakes.

SMTP Commands: Instructions that an email client communicates to the mail server to send an email.

502, "5.5.1"

Unimplemented command.

Ensure that your email client is using commands recognized by the SMTP server.

Unimplemented: Not yet put into effect.

503, "5.5.1"

"EHLO/HELO first.

Your email client may be out of order. Ensure it starts with an EHLO or HELO command.

EHLO/HELO: Commands used by SMTP to initiate the connection.

503, "5.5.1"

MAIL first.

The MAIL command needs to be the first command in your SMTP conversation.

MAIL: An SMTP command is used to initiate mail transfer.

503, "5.5.1"

RCPT first.

The RCPT command needs to be the first command in your SMTP conversation.

RCPT: An SMTP command is used to identify the email's recipient.

503, "5.7.0"

No identity changes are permitted.

Check your SMTP configuration or contact your service provider.

Identity: The unique identifier (often a username or email address) associated with a specific user.

504, "5.7.4"

Unrecognized Authentication Type

Check your SMTP settings and ensure you're using a supported authentication type.

Authentication Type: The method used to verify a user's identity, such as password or OAuth.

530, "5.5.1"

Authentication Required

Check that you're properly authenticated with your SMTP credentials.

Authentication: The process of verifying a user's identity.

530, "5.7.0"

Must issue a STARTTLS command first

Ensure that your email client initiates the SMTP connection with a STARTTLS command.

STARTTLS: A way to take an existing insecure connection and upgrade it to a secure connection using SSL/TLS.

535, "5.5.4"

Optional Argument not permitted for that AUTH mode

Check your SMTP settings, especially the AUTH command and its arguments.

AUTH: An SMTP command is used to authenticate the client to the server.

535, "5.7.1"

Application-specific password required

Use an application-specific password if you have 2-Step Verification enabled.

Application-specific password: A password for applications not supporting logging in using 2-Step Verification.

535, "5.7.1"

Please log in with your web browser and then try again

Log into your account via your web browser, then resend your email.

535, "5.7.1"

Username and Password not accepted

Ensure that you're entering the correct username and password. If you're using 2-Step Verification, use an application-specific password.

550, "5.1.1"

The email account that you tried to reach does not exist

Check the recipient's email address for typos or unnecessary spaces.

550, "5.2.1"

The email account that you tried to reach is disabled

You cannot send an email to a disabled account. Contact the recipient through other means if possible.

550, "5.2.1"

The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered

Try again later.

550, "5.4.5"

Daily sending quota exceeded

Limit the number of emails you send each day or upgrade your Google Workspace edition if you need to send more mail.

Quota: A set limit on how much of a particular resource a user or program can use.

550, "5.4.5"

Daily SMTP relay limit exceeded for user

Check your SMTP relay settings or upgrade your Google Workspace edition to send more mail.

SMTP relay: A service used to send large volumes of email.

550, "5.7.0"

Mail relay denied

The email was not sent because the SMTP relay was denied; contact your service provider.

Relay: The act of passing email from one server to another.

550, "5.7.0"

Mail Sending denied

Ensure the sender account is active and part of your Google Workspace domain.

550, "5.7.1"

Email quota exceeded

You'll need to free up storage space or purchase more in order to send additional emails.

Quota: A set limit on how much of a particular resource a user or program can use.

550, "5.7.1"

Invalid credentials for relay

Check the configuration of your SMTP relay service.

Credentials: Information that includes identification and proof of identification used to gain access to resources.

550, "5.7.1"

Our system has detected an unusual rate of unsolicited mail originating from your IP address.

If you're not sending spam, examine your network for malware or misconfigured software.

Unsolicited mail: Email that a user did not ask for (usually refers to spam).

550, "5.7.1"

Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked

Ensure the email complies with Gmail’s Bulk Email Senders Guidelines

Unsolicited mail: Email that a user did not ask for (usually refers to spam).

550, "5.7.1"

The IP you're using to send mail is not authorized to send email directly to our servers

Use the SMTP relay at your service provider instead

SMTP relay: A service used to send large volumes of email.

550, "5.7.1"

The user or domain that you are sending to (or from) has a policy that prohibits the mail that you sent

Review the email content and contact the domain administrator for further details.

Policy: A rule or set of rules governing how systems or organizations operate.

550, "5.7.1"

Unauthenticated email is not accepted from this domain

Check your SMTP settings and ensure the email passes SPF or DKIM authentication

Unauthenticated email: An email that hasn't passed validation checks to prove it came from the domain it claims to be from.

550, "5.7.1"

Daily SMTP relay limit exceeded for customer

Check your SMTP relay settings or upgrade your Google Workspace edition if you need to send more mail

SMTP relay: A service used to send large volumes of email.

550, "5.7.26"

Unauthenticated email from domain name is not accepted due to domain's DMARC policy.

Adjust your DMARC records, consider using a service like Google Workspace to send your mail, and contact the administrator of the receiving mail server.

DMARC: An email validation system that detects and prevents email spoofing.

550, "5.7.26"

This message does not have authentication information or fails to pass authentication checks.

Ensure the email passes SPF or DKIM authentication

Authentication: The process of verifying the identity of a user, process, or device.

550, "5.7.26"

This message fails to pass SPF checks for an SPF record with a hard fail policy.

Adjust your SPF records and ensure the email passes SPF authentication

SPF (Sender Policy Framework): An email authentication method designed to detect forging sender addresses during email delivery.

552, "5.2.2"

The email account that you tried to reach is over quota

Ask the recipient to clear some space in their inbox

Quota: A set limit on how much of a particular resource a user or program can use

552, "5.2.3"

Your message exceeded Google's message size limits

Reduce the size of the message and try again

553, "5.1.2"

We weren't able to find the recipient domain

Double-check the recipient's email address for typos or unnecessary spaces

Domain: The part of an email address that comes after the @ symbol.

554, "5.6.0"

The mail message is malformed. Not accepted

Check the format of your email and try again

Malformed: Structured incorrectly or in a way that does not conform to the expected format.

554, "5.6.0"

Message exceeded 50 hops; this may indicate a mail loop

Check your SMTP settings to prevent potential mail loops

Mail Loop: A situation in which an email message is continually bounced back and forth between two or more servers.

554, "5.7.0"

This message was blocked because its content presents a potential security issue.

Ensure the content and attachments of the email comply with Google’s policies.

554, "5.7.0"

IP has been blacklisted due to spam activity

Contact your service provider and take steps to remove your IP from the blacklist.

Blacklist: A list of entities blocked or denied access to a certain system or protocol.

554, "5.7.1"

The transaction failed because the recipient's mailbox is full

Ask the recipient to clear some space in their mailbox

Mailbox: An electronic folder where incoming emails are stored for a user.

554, "5.7.1"

The message you're trying to send exceeds the recipient's size limits

Reduce the size of the message or contact the recipient to increase their size limits

Size limits: Restrictions on the maximum size of an email message or attachment.

555, "5.5.2"

Syntax error

Check the syntax of the email addresses, commands, or configuration settings.

Syntax: The set of rules that dictate the structure and format of a language or code.

555, "5.5.4"

Optional Argument not permitted for that AUTH mode

Review your SMTP authentication settings and ensure they are correctly configured

Authentication: The process of verifying the identity of a user, process, or device.

555, "5.7.1"

Authentication required for relay

Provide valid authentication credentials for the SMTP relay

Relay: Forwarding email messages from one mail server to another.

555, "5.7.1"

Please log in with your web browser and then try again

Access your Gmail account via a web browser and follow any on-screen prompts to resolve the issue

Web browser: A software application used to access and view websites.

555, "5.7.1"

Username and Password not accepted

Verify the correctness of your username and password, and ensure they are correctly entered.

Username: A unique identifier used to access a system or service.

550, "5.1.1"

The email account that you tried to reach does not exist

Double-check the recipient's email address for typos, or contact the recipient to confirm the correct email address

Typos: Errors or mistakes in the spelling or formatting of text.

550, "5.2.1"

The email account that you tried to reach is disabled

Verify the status of the recipient's email account or contact the recipient to confirm the account status

Disabled: Inactive or deactivated.

550, "5.4.5"

Daily sending quota exceeded

Reduce the number of outgoing emails or upgrade your Google Workspace edition for higher sending quotas.

I am sending quota: The maximum number of emails allowed to be sent within a specified time period.

550, "5.4.5"

Daily SMTP relay limit exceeded for user

Check your SMTP relay sending limits or contact your administrator for assistance

SMTP relay: A service used to send large volumes of email.

550, "5.7.0"

Mail relay denied

Check your SMTP relay settings and ensure they comply with Google's policies.

Mail relay: Forwarding email messages from one mail server to another.

550, "5.7.0"

Mail Sending denied. This error occurs if the sender account is disabled or not registered within your Google Workspace domain.

Verify the sender's email account status and ensure it is enabled and registered within the Google Workspace domain.

Domain: A group of computers or devices that share a common set of rules and settings.

550, "5.7.1"

Email quota exceeded

Reduce your mailbox size or upgrade your Google Workspace edition for higher storage quotas.

Quota: The allocated amount or limit for a particular resource or service.

550, "5.7.1"

Invalid credentials for relay

Verify the correctness of your authentication credentials for the SMTP relay.

Credentials: Information used to verify one's identity or access a system.

550, "5.7.1"

Our system has detected an unusual rate of unsolicited mail originating from your IP address.

Check your network for malware or misconfigured software to prevent spamming activities.

Unsolicited mail: Email that is sent without the recipient's explicit consent.

550, "5.7.1"

The IP you're using to send mail is not authorized to send emails directly to our servers.

Use the SMTP relay provided by your service provider to send an email or contact Google support for further assistance

SMTP: Simple Mail Transfer Protocol, the standard protocol used for email transmission.

550, "5.7.1"

The user or domain that you are sending to (or from) has a policy that prohibits the mail that you sent

Review and comply with the policies of the recipient's user or domain to ensure successful email delivery.

Policies: Rules or guidelines that govern the behavior or actions within a system or organization.

550, "5.7.1"

Unauthenticated email is not accepted from this domain

Configure your email client or server to authenticate before sending emails

Authentication: The process of verifying the identity or legitimacy of a user or entity.

550, "5.7.1"

Daily SMTP relay limit exceeded for customer

Review your SMTP relay sending limits or contact your administrator for assistance.

SMTP relay: A service used to send large volumes of email.

550, "5.7.26"

Unauthenticated email from domain name is not accepted due to domain's DMARC policy

Authenticate your email with the appropriate mechanisms specified by the DMARC policy of the recipient's domain.

DMARC: Domain-based Message Authentication, Reporting, and Conformance, a security protocol for preventing email spoofing.

550, "5.7.26"

This message does not have authentication information or fails to pass authentication checks (SPF or DKIM)

Ensure your email passes SPF and DKIM authentication checks to improve deliverability.

SPF: Sender Policy Framework, a protocol that validates the origin of email messages. DKIM: DomainKeys Identified Mail, a method for validating the authenticity of email messages.

552, "5.2.2"

The email account that you tried to reach is over quota

Advise the recipient to free up space in their mailbox by deleting unnecessary emails

Quota: The allocated storage capacity for an email account.

552, "5.2.3"

Your message exceeded Google's message size limits

Reduce the size of your email message or use alternative methods for sharing large files

Message size limits: The maximum allowed size for an email message, including attachments.

553, "5.1.2"

We weren't able to find the recipient domain

Verify the correctness of the recipient's email address and check for any typos or formatting errors.

Domain: The part of an email address after the "@" symbol indicating the recipient's email server.

554, "5.6.0"

The mail message is malformed. Not accepted

Review the structure and content of your email message for any errors or inconsistencies.

Malformed: Incorrectly structured or formatted.

554, "5.6.0"

Message exceeded 50 hops; this may indicate a mail loop

Investigate and resolve any circular forwarding or routing configurations causing the mail loop

Mail loop: A situation where an email is continuously forwarded or routed between multiple recipients.

554, "5.7.0"

Too Many Unauthenticated commands

Review your SMTP authentication settings and ensure proper authentication during the SMTP session.

Unauthenticated commands: SMTP commands are issued without proper authentication.

555, "5.5.2"

Syntax error

Double-check the syntax and format of email addresses, commands, or configuration settings.

Syntax: The rules and structure that govern the correct arrangement of elements in a language or code.

Error Codes for Outlook:

Error Category

Error Codes

Meaning

Troubleshooting

Glossary

General Errors

0x800CCC00

This error suggests that the authentication did not load, which might be a result of invalid login details or a problem with the server.

Recheck your email and password details to ensure they are correct. If the problem persists, try restarting your mail server or contact your ISP for support.

ISP: Internet Service Provider

General Errors

0x800CCC01

Invalid certificate content - the certificate content that Outlook is trying to use for a secured connection is invalid.

Verify that all necessary intermediate certificates are installed. If the certificate is self-signed, make sure that the same certificate is installed on both the client and server machines.

Intermediate certificates: These are certificates that are part of the certification path. They connect your certificate to the root certificate of the certificate authority.

General Errors

0x800CCC02

This indicates an invalid certificate date.

Check the certificate's validity period. It might have expired, in which case you need to renew it.

Certificate validity period: The time frame in which a certificate is considered valid. Once expired, it must be renewed.

General Errors

0x800CCC03

User already connected. This means there's another session that's already connected to the mail server.

Disconnect the other session or try again later. Check for multiple instances of Outlook.

Session: A session represents a single period of user interaction with your app.

General Errors

0x800CCC04

General Errors

0x800CCC05

This suggests that Outlook is not connected to the server.

Check your internet connection. If it is stable, there might be issues with the server. Contact your ISP for help.

Server: A server is a computer that provides data to other computers.

General Errors

0x800CCC06

General Errors

0x800CCC07

General Errors

0x800CCC08

General Errors

0x800CCC09

General Errors

0x800CCC0A

Message download incomplete - this happens when Outlook is unable to fully download an email message from the server.

Check your internet connection or try deleting and re-downloading the email.

Download: The process of getting data from a server to your device.

General Errors

0x800CCC0B

Server or maildrop is busy. This suggests that the server is overwhelmed with requests.

Try again later when the server might be less busy. If the problem persists, it could be a server-side issue and you might need to contact your ISP.

Maildrop: A maildrop is a location where mail is stored until it is collected.

General Errors

0x800CCC0C

General Errors

0x800CCC0D

Cannot locate server. This means Outlook is unable to establish a connection with your mail server.

Check your server settings, ensure that you have the correct server address, and that your internet connection is active.

Server settings: These are the specific requirements and information needed to connect to a server.

General Errors

0x800CCC0E

Cannot connect to server. A connection could not be made to the email server.

Check your internet connection, firewall settings and server settings. If everything appears to be correct, there could be a server-side issue.

Firewall: This is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

General Errors

0x800CCC0F

Connection dropped - this means the connection to the server was interrupted.

Check your internet connection, and ensure your email settings are correct. If the problem persists, it could be a server-side issue.

Server-side: This refers to operations that are performed by the server in a client-server relationship.

General Errors

0x800CCC10

Invalid address - this error occurs when the email address is not valid or correctly entered.

Double-check the email address for any errors or missing information.

Email address: This is an identifier for an email box to which email messages are delivered.

General Errors

0x800CCC11

Invalid address list - the list of addresses is not valid.

Check to make sure all the addresses in your list are formatted correctly and remove any that are not.

Address list: This is a collection of mail-enabled recipient objects in Exchange Online.

General Errors

0x800CCC12

Socket read error - this occurs when Outlook cannot read from the network.

Check your network connection. If the problem persists, try restarting your computer or contact your ISP.

Socket: A socket represents a single connection between two network applications.

General Errors

0x800CCC13

Socket write error - this occurs when Outlook cannot write data to the network.

Check your network connection. If the problem persists, try restarting your computer or contact your ISP.

Write: In computing, writing data refers to the process of entering data into a computer system or storage medium.

General Errors

0x800CCC14

Socket initialization error - this error occurs when Outlook cannot initialize the network connection.

Check your network settings, and ensure your internet connection is active. If the problem persists, try restarting your computer or contact your ISP.

Initialization: The process of locating and using the defined values for variable data that is used by a computer program.

General Errors

0x800CCC15

Socket connect error - this error means that Outlook cannot establish a network connection.

Check your network connection and settings. If the problem persists, try restarting your computer or contact your ISP.

Network connection: This refers to the setup that allows the exchange of data between two or more network devices.

General Errors

0x800CCC16

Invalid account - the user account on the mail server is invalid.

Verify your account details with your email provider. Ensure you are entering the correct username and password.

User account: This is a location on a network server where a user has access to personal files and settings.

General Errors

0x800CCC17

User canceled operation - the user canceled the operation before it was complete.

If you did not intentionally cancel the operation, try again. If the problem persists, there may be an issue with your email client or ISP.

Email client: This is an application used to manage a user's email.

General Errors

0x800CCC18

Logon failure: unknown user name or bad password - the username or password is incorrect.

Re-enter your username and password carefully to ensure they are correct. If the problem persists, you may need to reset your password or contact your ISP.

Logon: This is the process of gaining access to a computer system or network by entering a username and password.

General Errors

0x800CCC19

Timeout - this error occurs when a network operation in Outlook times out.

Check your network connection. If it is stable, the server might be slow or overloaded. Try again later.

Timeout: This is a designated amount of time that a program or system will wait for a response before it gives up.

General Errors

0x800CCC1A

Security error - this means that there's a problem with the SSL or TLS security protocols.

Make sure you're using the correct security settings in your email client. If necessary, you can temporarily disable SSL/TLS to see if that's causing the problem.

SSL/TLS: These are cryptographic protocols designed to provide secure communication over a computer network.

General Errors

0x800CCC1B

Server does not support the requested encryption type - the server doesn't support the encryption method specified in your email client.

Make sure your email client's encryption settings match what your email server supports. You may need to contact your email provider for the correct settings.

Encryption: This is the method by which information is converted into a secret code that hides the information's true meaning.

General Errors

0x800CCC1C

Not able to access the account - the user can't access the email account.

Double check your username and password. If you're certain they're correct, your email account might be temporarily locked or there might be a problem with the mail server.

Mail server: This is a computerized system that sends and receives email.

General Errors

0x800CCC1D

No server response - the server isn't responding to requests.

This might be a temporary problem with the mail server. If it persists, contact your email provider.

Server response: This refers to the reply by the server after it has processed the client's request.

General Errors

0x800CCC1E

Unable to connect to the account - the email client can't connect to the email account.

Double check your email client settings, including username, password, and mail server. If everything seems correct, there might be a problem with the mail server.

Connect: This refers to establishing a network connection for communication between devices.

General Errors

0x800CCC1F

Server response timeout - the server took too long to respond.

This is typically a problem with the server. You could try to connect again later, or contact your email provider if the problem persists.

Server response timeout: This is when the server fails to respond to a request from a client within a given time period.

General Errors

0x800CCC20

Unable to find the email server - the email client can't find the mail server.

Make sure you've entered the correct server address in your email client settings. If the problem persists, contact your email provider.

Server address: This is the unique identification of a server, often an IP address or a URL.

General Errors

0x800CCC21

Server response error - the server responded with an error.

The exact problem will depend on the error message. It could be a temporary server problem, or it might indicate a problem with your email client settings.

Error message: This is a message displayed when an unexpected condition occurs, usually on a computer or other device.

General Errors

0x800CCC22

Server response fail - this means the server has failed to respond as expected.

Try again later, as this could be a temporary server issue. If the problem persists, contact your email provider.

Server response: This refers to the server's reply after processing the client's request.

General Errors

0x800CCC23

Authentication failed - the email client has failed to authenticate with the email server.

Check your email client settings, including username and password. If they are correct, contact your email provider.

Authentication: This is the process of verifying the identity of a user or system.

General Errors

0x800CCC24

Network connection failure - there is a problem with the network connection.

Check your internet connection. If other internet-based applications are working fine, the problem might lie with your email server.

Network connection: This refers to the link between two or more computers or systems allowing them to share resources.

General Errors

0x800CCC25

SSL connection failure - the SSL connection to the email server has failed.

Make sure your email client is correctly configured for SSL. If necessary, you can temporarily disable SSL to see if that's causing the problem.

SSL: Secure Sockets Layer, a protocol for web browsers and servers that allows for the authentication, encryption and decryption of data sent over the Internet.

General Errors

0x800CCC26

Unknown error - an unspecified error has occurred.

As this error is quite generic, there could be various potential causes. Restart your email client, and if the problem persists, contact your email provider.

Unknown error: An error where the root cause is not identified.

General Errors

0x800CCC27

Out of memory - there isn't enough memory to complete the requested task.

Close unnecessary applications to free up memory. If the problem persists, your computer might not have enough memory to run your email client.

Out of memory: A condition where a system lacks sufficient memory to perform a task.

General Errors

0x800CCC28

Server doesn't support digital IDs - the email server doesn't support the digital ID feature.

This error typically requires a change in server settings. You might need to contact your email provider for help.

Digital ID: A digital equivalent of identification documents in physical form.

General Errors

0x800CCC29

User not authenticated on server - the server has not authenticated the user.

Re-enter your username and password in your email client. If they're correct and you're still getting this error, you might need to contact your email provider.

User authentication: The process of confirming a user's identity.

Winsock Errors

0x800CCC40

Network subsystem is unusable.

Try restarting your machine or reset your network settings. If the problem persists, you might need to check your network hardware or contact your ISP.

Network subsystem: It refers to the part of the operating system that is responsible for networking.

Winsock Errors

0x800CCC41

Windows Sockets cannot support this application.

Make sure that the application you are trying to run is compatible with your version of Windows. If necessary, look for an updated version of the application.

Windows Sockets (Winsock): It is a technical specification that defines how Windows network software should access network services, especially TCP/IP.

Winsock Errors

0x800CCC42

(As no specific description is given, generic advice would be to restart your machine and check for system updates.)

Winsock Errors

0x800CCC43

Bad address.

The error suggests that the address provided is invalid. Check the IP address you're using and ensure it's correct.

IP address: An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication.

Winsock Errors

0x800CCC44

Unable to load Windows Sockets.

Reinstall your network adapter drivers, and/or reset your network settings. If the problem persists, you might need to reinstall your operating system.

Network adapter drivers: These are software programs that enable a computer to communicate with a network.

Winsock Errors

0x800CCC45

Operation now in progress. This error appears if a Windows Sockets API is called while a blocking function is in progress.

Do not run blocking operations in parallel with other functions. Consider reorganizing your code to avoid this conflict.

Blocking operation: A function or process that stops the execution of the program until a particular condition is met.

SMTP Errors

0x800CCC60

Invalid response.

Check your server settings and verify that you're connecting to the correct server. If you're using an email client, try re-configuring the SMTP server settings.

SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers.

SMTP Errors

0x800CCC61

Unknown error code.

As this is an unspecified error, try restarting your email client or your computer. If the problem persists, reach out to your email provider for assistance.

SMTP Errors

0x800CCC62

Syntax error returned.

This error is generally related to incorrect email format or structure. Check the email you're trying to send for any unusual characters or structures and correct them.

Syntax error: A character or string incorrectly placed in a command or instruction, which causes a failure in execution.

SMTP Errors

0x800CCC63

Parameter syntax incorrect.

Ensure the command sent to the SMTP server is correct and follows the correct syntax. This could be related to email content or configuration settings.

Parameter: A value that the user provides to a command.

SMTP Errors

0x800CCC64

Command not implemented.

The command sent to the SMTP server may not be supported. Check the compatibility and requirements of your SMTP server.

Command: A directive to a computer program acting as an interpreter of some kind, in order to perform a specific task.

SMTP Errors

0x800CCC65

Improper command sequence.

Commands were sent to the SMTP server in the wrong order. Ensure the sequence of commands sent to the SMTP server is correct.

SMTP Errors

0x800CCC66

Command not implemented.

The command sent to the SMTP server may not be supported. Check the compatibility and requirements of your SMTP server.

SMTP Errors

0x800CCC67

Command not available.

The requested command is not available in the current context or server. Check if the server supports the command or if you're in the correct stage of the SMTP process.

SMTP Errors

0x800CCC68

Mailbox is locked and busy.

Wait a while and try again. If the problem persists, reach out to your email provider for assistance.

Mailbox: A destination to which email messages are delivered. It is usually associated with a single user.

SMTP Errors

0x800CCC69

Mailbox not found.

Ensure the recipient email address is correct. If it's correct and the issue persists, the recipient's email server may be misconfigured.

SMTP Errors

0x800CCC6A

Error processing request.

This is a server-side issue. The server had a problem processing the request. Try again later. If the problem persists, contact your email service provider.

SMTP Errors

0x800CCC6B

User mailbox is known but mailbox not on this server.

The email address you're trying to reach is valid, but the server you're connected to doesn't host the mailbox. Ensure your server settings are correct.

SMTP_551_USER_NOT_LOCAL

0x800CCC6C

No space to store messages.

The recipient's mailbox may be full. You can try again later or contact the recipient to ask them to free up some space in their mailbox.

SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail.

SMTP_551_USER_NOT_LOCAL

0x800CCC6D

Storage limit exceeded.

This error is typically a server side issue. It means the mailbox storage has been exceeded due to which the mail could not be sent. You can try again later, or contact your server admin/ISP.

SMTP: Simple Mail Transfer Protocol, ISP: Internet Service Provider.

SMTP_551_USER_NOT_LOCAL

0x800CCC6E

Invalid mailbox name syntax.

The syntax of the recipient's email address is not correct. Verify the email address and try again.

SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail.

SMTP_551_USER_NOT_LOCAL

0x800CCC6F

Transaction failed.

This error generally indicates a failure in the transmission of the email. It could be due to a variety of issues, including server problems, network issues, or email client problems. Check your internet connection, server settings, and email client settings.

SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail.

SMTP_551_USER_NOT_LOCAL

0x800CCC78

Unknown sender. This is caused by having the incorrect email address in the Reply-To field.

Verify the 'Reply-To' field in your email. It may be incorrectly filled. Make sure it is a valid email address and try sending again.

SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail.

SMTP_REJECTED_SENDER

0x800CCC79

Server rejected recipients.

This error usually occurs when the recipients' email addresses are not accepted by the server. Verify the recipients' email addresses, ensure they are valid and properly formatted, and try again.

SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail.

SMTP_REJECTED_SENDER

0x800CCC7A

No sender address specified.

This error occurs when there is no sender address specified in the email. Check your email client settings and make sure that your email address is correctly entered in the outgoing mail server settings.

SMTP_REJECTED_SENDER

0x800CCC7B

No recipients specified.

This error happens when no recipient email addresses have been specified. You need to specify at least one valid recipient email address before sending the email.

POP3 Errors

0x800420CB

Mail cannot be stored on the server.

This error occurs when the POP3 server is unable to store the incoming mail. Check the server settings, mailbox quota, and available storage space. Contact your email provider for assistance if needed.

POP3: Post Office Protocol 3, a standard protocol used for retrieving emails from a remote server.

POP3 Errors

0x800CCC90

Client response invalid.

This error indicates that the client response sent to the POP3 server is invalid or not recognized. Review the client configuration, ensure correct settings, and check for any software conflicts or network issues.

POP3 Errors

0x800CCC91

Invalid user name or user not found.

This error occurs when the provided username for the POP3 server is invalid or the user does not exist. Double-check the username, ensure it is entered correctly, and verify that the user account exists on the server.

POP3 Errors

0x800CCC92

Password not valid for account.

The error indicates an incorrect password provided for the POP3 account. Make sure the password is correct and properly entered. If necessary, reset the password and update the account settings in the email client.

POP3 Errors

0x800CCC93

Unable to interpret response.

This error suggests that the client is unable to interpret the response received from the POP3 server. Review the client configuration, ensure proper settings, and check for any software conflicts or network issues.

POP3 Errors

0x800CCC94

STAT Command required.

The POP3 server requires the STAT command to be executed before performing any further operations. Make sure the client is issuing the STAT command to retrieve the necessary information.

STAT Command: A command in POP3 that retrieves the status of the mailbox, including the number of messages and the total size.

POP3 Errors

0x800CCC95

No messages on the server.

This error indicates that there are no messages available on the POP3 server. Check if any new messages are present in the mailbox or contact your email provider for assistance.

POP3 Errors

0x800CCC96

No messages marked for retrieval.

The error occurs when there are no messages marked for retrieval on the POP3 server. Ensure that messages are marked correctly for retrieval and try again.

POP3 Errors

0x800CCC97

Message ID out of range.

This error suggests that the requested message ID is out of range or does not exist on the POP3 server. Check the message ID and verify its availability on the server.

IMAP Errors

0x800CCCD1

The login attempt to the IMAP server has failed. Double-check the username and password, ensure they are correct, and verify that the server settings are accurate. If the issue persists, contact your email provider for further assistance.

IMAP: Internet Message Access Protocol, a standard protocol used for accessing and retrieving emails from a remote server.

IMAP Errors

0x800CCCD2

Message tagged.

This error indicates that the server has tagged the message but is not providing a response. Check the server status, network connection, and email client configuration. Retry the operation after ensuring a stable connection.

IMAP Errors

0x800CCCD3

Invalid response to request.

The server has returned an invalid response to the IMAP request. Verify the request sent by the client, check for any syntax errors or issues with the request format. Ensure the email client is compatible with the server's IMAP version.

IMAP Errors

0x800CCCD4

Syntax error.

The server has encountered a syntax error in the command or response. Review the command or response syntax, ensure it complies with the IMAP protocol specifications. Correct any syntax errors in the client configuration or request.

IMAP Errors

0x800CCCD5

Not an IMAP server.

The server being accessed is not recognized as an IMAP server. Verify the server settings, ensure the correct protocol (IMAP) is selected, and confirm the server's compatibility with IMAP.

IMAP Errors

0x800CCCD6

Buffer limit exceeded.

The IMAP server has exceeded the buffer limit. This can happen if the server is receiving a large amount of data or if there is an issue with the server configuration. Contact your email provider or system administrator for further assistance.

IMAP Errors

0x800CCCD7

Recovery error.

An error occurred during the recovery process. This can happen if the server is experiencing issues or if there is a problem with the mailbox. Contact your email provider for assistance in resolving the recovery error.

IMAP Errors

0x800CCCD8

Incomplete data.

The server has provided an incomplete response or data. Check the network connection, verify the server status, and ensure there are no interruptions or issues with the communication between the client and server.

IMAP Errors

0x800CCCD9

Connection not allowed.

The IMAP connection is not allowed by the server. This can occur due to server configuration or security restrictions. Contact your email provider or system administrator to verify the connection settings and permissions.

IMAP Errors

0x800CCCDA

Unknown response.

The server has returned an unknown or unrecognized response. Check the request sent by the client, verify the server compatibility, and ensure the client configuration is correct. If the issue persists, contact your email provider for further assistance.

IMAP Errors

0x800CCCDB

User ID has changed.

The user ID associated with the IMAP account has changed. Review the user ID and update it in the email client's account settings. Contact your email provider if you are unsure about the correct user ID to use.

IMAP Errors

0x800CCCDC

User ID command failed.

The command related to the user ID has failed on the IMAP server. Verify the user ID command syntax, ensure it complies with the IMAP protocol. Check for any issues with the server configuration or network connectivity.

IMAP Errors

0x800CCCDD

Unexpected disconnect.

The connection to the IMAP server was unexpectedly disconnected. Check the network connection, ensure there are no interruptions or network issues. Retry the operation and monitor for any further disconnects.

IMAP Errors

0x800CCCDE

Invalid server state.

The IMAP server is in an invalid or improper state. This can happen due to server issues or conflicts. Contact your email provider or system administrator for assistance in resolving the server state issue.

IMAP Errors

0x800CCCDF

Unable to authorize client.

The client is unable to authorize with the IMAP server. Check the client's authentication settings, ensure the username and password are correct. Verify that the server supports the chosen authentication method. Contact your email provider for further assistance.

IMAP Errors

0x800CCCE0

No more authorization types.

The IMAP server does not support any more available authorization types. Verify the client's authentication settings, ensure the selected authorization type is supported by the server. Contact your email provider for further guidance.

NNTP Errors

0x800CCCA0

News server response error.

This error indicates an error in the response received from the NNTP server. Check the network connection, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection.

NNTP Errors

0x800CCCA1

Newsgroup access failed.

The access to the newsgroup on the NNTP server has failed. Ensure the newsgroup exists, check the server settings, and verify that the client has appropriate permissions. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA2

LIST command to server failed.

The LIST command issued to the NNTP server has failed. Review the command syntax, verify the server compatibility, and check for any network connectivity issues. Retry the command after ensuring a stable connection.

LIST A Commant in NNTP that retrives a list of available newsgroups on the server

NNTP Errors

0x800CCCA3

Unable to display list.

This error suggests that the client is unable to display the list of newsgroups on the NNTP server. Check the client configuration, verify the server compatibility, and ensure proper authentication if required. Retry the operation after ensuring a stable connection.

NNTP Errors

0x800CCCA4

Unable to open group.

The client is unable to open a specific newsgroup on the NNTP server. Verify the newsgroup name, check the server settings, and ensure proper permissions to access the newsgroup. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA5

Group not on server.

This error indicates that the requested newsgroup is not available on the NNTP server. Verify the newsgroup name, ensure it exists on the server, and check for any spelling errors. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA6

Message not on server.

The requested message is not available on the NNTP server. Check the message ID, verify its existence on the server, and ensure proper command syntax. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA7

Message header not found.

This error suggests that the header of the requested message is not found on the NNTP server. Check the message ID, verify its availability, and ensure proper command syntax. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA8

Message body not found.

The body of the requested message is not found on the NNTP server. Check the message ID, verify its availability, and ensure proper command syntax. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCA9

Unable to post to server.

The client is unable to post or submit a message to the NNTP server. Check the client configuration, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection.

NNTP Errors

0x800CCCAA

Unable to post to server.

This error indicates that the client is unable to post or submit a message to the NNTP server. Check the client configuration, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection.

NNTP Errors

0x800CCCAB

Unable to display date.

The client is unable to display the date of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCAC

Unable to display headers.

This error suggests that the client is unable to display the headers of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCAD

Unable to display MIME headers.

The client is unable to display the MIME headers of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed

NNTP Errors

0x800CCCAE

Invalid user or password.

This error indicates that the provided user or password is invalid for the NNTP server. Verify the user credentials, check for any spelling errors, and ensure proper authentication. Contact your news server provider for further assistance if needed.

NNTP Errors

0x800CCCC2

RAS/DUN not installed.

This error indicates that the Remote Access Service (RAS) or Dial-Up Networking (DUN) is not installed on the system. Install the necessary components or enable the required services for RAS/DUN functionality.

RAS Errors

0x800CCCC3

RAS/DUN process not found.

The RAS/DUN process is not found on the system. Verify that the required processes are running or restart the system to ensure the proper initialization of RAS/DUN components.

RAS Errors

0x800CCCC4

RAS/DUN error returned.

This error suggests that an error was returned by the RAS/DUN process. Check the specific error code or description associated with the error to determine the cause. Troubleshoot based on the specific error returned by the RAS/DUN process.

RAS Errors

0x800CCCC5

ConnectOID damaged or missing.

This error indicates that the ConnectOID used for connection is damaged or missing. Verify the configuration settings, check for any missing or corrupted files related to ConnectOID, and ensure proper initialization of the connection settings.

ConnectOID: Connect Object Identifier,a unique identifier used for establishing connections

RAS Errors

0x800CCCC6

Error getting dial settings.

This error suggests that there was an error while retrieving the dial-up settings. Verify the dial-up configuration, check for any issues with the network adapter or modem, and ensure proper settings for establishing a dial-up connection.