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 a Hard Bounce. Soft Bounce reasons can't be viewed through a Smart List report, only one at a time in a lead's activity log.
*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. |
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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 |
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