Email Bounce Codes
Traditional Bounce Codes
When you add the Email Invalid Cause to display as a Column to any of your Deliverability Smartlists, you will see a code value, and potentially a suffix as well, to help you understand the reason for the Bounce.
- Codes in the 400 range are generally Soft Bounces
- Codes in the 500 range are generally Hard Bounces
Mail server administrators can create custom messages that accompany bounce codes
|
Code |
Explanation |
|
250 |
Mail accepted by receiving network |
|
421 |
<domain> Service not available, closing transmission channel |
|
450 |
Requested mail action not taken: mailbox unavailable (e.g., mailbox busy) |
|
451 |
Requested action aborted: error in processing |
|
452 |
Requested action not taken: insufficient system storage |
|
500 |
The server could not recognize the command due to a syntax error. |
|
501 |
A syntax error was encountered in command arguments. |
|
502 |
This command is not implemented. |
|
503 |
The server has encountered a bad sequence of commands. |
|
504 |
A command parameter is not implemented. |
|
550 |
User’s mailbox was unavailable (such as not found) |
|
551 |
The recipient is not local to the server. |
|
552 |
The action was aborted due to exceeded storage allocation. |
|
553 |
The command was aborted because the mailbox name is invalid. |
|
554 |
The transaction failed for some unstated reason. |
Enhanced Bounce Codes
If a suffix appears after one of the codes above, it is an enhanced Bounce code
Mail server administrators can crate custom messages that accompany bounce codes
|
Code |
Explanation |
|
5.0.0 |
Address does not exist |
|
5.1.0 |
Other address status |
|
5.1.1 |
Bad destination mailbox address |
|
5.1.2 |
Bad destination system address |
|
5.1.3 |
Bad destination mailbox address syntax |
|
5.1.4 |
Destination mailbox address ambiguous |
|
5.1.5 |
Destination mailbox address valid |
|
5.1.6 |
Mailbox has moved |
|
5.1.7 |
Bad sender’s mailbox address syntax |
|
5.1.8 |
Bad sender’s system address |
|
5.2.0 |
Other or undefined mailbox status |
|
5.2.1 |
Mailbox disabled, not accepting messages |
|
5.2.2 |
Mailbox full |
|
5.2.3 |
Message length exceeds administrative limit. |
|
5.2.4 |
Mailing list expansion problem |
|
5.3.0 |
Other or undefined mail system status |
|
5.3.1 |
Mail system full |
|
5.3.2 |
System not accepting network messages |
|
5.3.3 |
System not capable of selected features |
|
5.3.4 |
Message too big for system |
|
5.4.0 |
Other or undefined network or routing status |
|
5.4.1 |
No answer from host |
|
5.4.2 |
Bad connection |
|
5.4.3 |
Routing server failure |
|
5.4.4 |
Unable to route |
|
5.4.5 |
Network congestion |
|
5.4.6 |
Routing loop detected |
|
5.4.7 |
Delivery time expired |
|
5.5.0 |
Other or undefined protocol status |
|
5.5.1 |
Invalid command |
|
5.5.2 |
Syntax error |
|
5.5.3 |
Too many recipients |
|
5.5.4 |
Invalid command arguments |
|
5.5.5 |
Wrong protocol version |
|
5.6.0 |
Other or undefined media error |
|
5.6.1 |
Media not supported |
|
5.6.2 |
Conversion required and prohibited |
|
5.6.3 |
Conversion required but not supported |
|
5.6.4 |
Conversion with loss performed |
|
5.6.5 |
Conversion failed |
|
5.7.0 |
Other or undefined security status |
|
5.7.1 |
Delivery not authorized, message refused |
|
5.7.2 |
Mailing list expansion prohibited |
|
5.7.3 |
Security conversion required but not possible |
|
5.7.4 |
Security features not supported |
|
5.7.5 |
Cryptographic failure |
|
5.7.6 |
Cryptographic algorithm not supported |
|
5.7.7 |
Message integrity failure |