It is important to figure out why your email bounces. If you receive an email bounce, you can look in the bounce message to find the proper error code that will give you the reason for the bounce. Below is a list of the Standard SMTP error codes and the Extended SMTP (ESMTP) error codes.

SMTP Error Codes

This list of codes is the standard SMTP error codes you will find in most email bounces.

200 Codes

  • 211 - System status / system help reply
  • 214 - Help message
  • 220 - Domain service ready
  • 221 - Domain service closing transmission channel
  • 250 - Requested mail action completed and OK
  • 251 - Not Local User, forward email to forward path
  • 252 - Cannot Verify user, will attempt delivery later
  • 253 - Pending messages for node started

300 Codes

  • 354 - Start mail input; end with .
  • 355 - Octet-offset is the transaction offset

400 Codes

500 Codes

Extended SMTP (ESMTP) standards

The Extended SMTP error codes work in 3 digit combinations. For example, 5.2.1 is a Permanent Error where the receiving email is not accepting messages. The first number is the email message status. The second 2 numbers pinpoint the exact information bout the error.

  • 2 Successfully sent the email;
  • 4 Temporary problem when sending the email. The email server typically will try to send it again till it reaches retry timeout.
  • 5 Permanent or Fatal error. This can be caused by a non existent email address, DNS problem, or your email was blocked by the receiving server.

Below is a list of the Extended SMTP error codes.

Note! X can be a 4 or a 5 depending on is its Temporary or Permanent.

x.1.x Codes

  • X.1.0 - Other address status
  • X.1.1 - Bad destination mailbox address
  • X.1.2 - Bad destination system address
  • X.1.3 - Bad destination mailbox address syntax
  • X.1.4 - Destination mailbox address ambiguous
  • X.1.5 - Destination mailbox address valid
  • X.1.6 - Mailbox has moved
  • X.1.7 - Bad sender's mailbox address syntax
  • X.1.8 - Bad sender's system address

x.2.x Codes

  • X.2.0 - Other or undefined mailbox status
  • X.2.1 - Mailbox disabled, not accepting messages
  • X.2.2 - Mailbox full
  • X.2.3 - Message length exceeds administrative limit
  • X.2.4 - Mailing list expansion issue

x.3.x Codes

  • X.3.0 - Other or undefined mail system status
  • X.3.1 - Mail system full
  • X.3.2 - System not accepting network messages
  • X.3.3 - System not capable of selected features
  • X.3.4 - Message too big for system
  • X.3.5 - System incorrectly configured

x.4.x Codes

  • X.4.0 - Other or undefined network or routing status
  • X.4.1 - No answer from host
  • X.4.2 - Bad connection
  • X.4.3 - Routing server failure
  • X.4.4 - Unable to route
  • X.4.5 - Network congestion
  • X.4.6 - Routing loop detected
  • X.4.7 - Delivery time expired

x.5.x Codes

  • X.5.0 - Other or undefined protocol status
  • X.5.1 - Invalid command
  • X.5.2 - Syntax error
  • X.5.3 - Too many recipients
  • X.5.4 - Invalid command arguments
  • X.5.5 - Wrong protocol version

x.6.x Codes

  • X.6.0 - Other or undefined media error
  • X.6.1 - Media not supported
  • X.6.2 - Conversion required and prohibited
  • X.6.3 - Conversion required but not supported
  • X.6.4 - Conversion with loss performed
  • X.6.5 - Conversion failed

x.7.x Codes

  • X.7.0 - Other or undefined security status
  • X.7.1 - Delivery not authorized, message refused
  • X.7.2 - Mailing list expansion prohibited
  • X.7.3 - Security conversion required but not possible
  • X.7.4 - Security features not supported
  • X.7.5 - Cryptographic failure
  • X.7.6 - Cryptographic algorithm not supported
  • X.7.7 - Message integrity failure
Did you find this article helpful?

We value your feedback!

Why was this article not helpful? (Check all that apply)
The article is too difficult or too technical to follow.
There is a step or detail missing from the instructions.
The information is incorrect or out-of-date.
It does not resolve the question/problem I have.
How did you find this article?
Please tell us how we can improve this article:
Email Address
Name

new! - Enter your name and email address above and we will post your feedback in the comments on this page!

Related Questions

Here are a few questions related to this article that our customers have asked:
Ooops! It looks like there are no questions about this page.
Would you like to ask a question about this page? If so, click the button below!
Ask a Question
n/a Points
2014-03-22 10:14 am

Thank you. The listing helps me explain better to users.

n/a Points
2014-12-15 2:33 am

404 not found, its clear explanation, can't access the webmail login page

 

Staff
20,848 Points
2014-12-15 12:09 pm
Hello Swetha,

404 is not an SMTP error but a server error when it cannot find a page. Are you getting this error when trying to log in? If so, what is the URL you are trying to log into?

Kindest Regards,
Scott M

Post a Comment

Name:
Email Address:
Phone Number:
Comment:
Submit

Please note: Your name and comment will be displayed, but we will not show your email address.

3 Questions & Comments

Post a comment

Back to first comment | top

Need more Help?

Search

Ask the Community!

Get help with your questions from our community of like-minded hosting users and InMotion Hosting Staff.

Current Customers

Chat: Click to Chat Now E-mail: support@InMotionHosting.com
Call: 888-321-HOST (4678) Ticket: Submit a Support Ticket

Not a Customer?

Get web hosting from a company that is here to help. Sign up today!