Addressing
Recipient address validity, syntax, destination selection, and address-related routing.
This category brings together seven reviewed codes covering address validity and syntax, destination selection, and routing derived from an address. It includes a positive confirmation that a destination address is valid, temporary conditions involving the recipient mailbox or the system identified by the sender address, and permanent outcomes for a nonexistent mailbox, invalid recipient-address syntax, an invalid sender-system address, and a recipient domain marked by a null MX. Meaning always depends on the complete code, especially class 2, 4, or 5; the category alone does not determine whether a report records success, a temporary condition, or a permanent failure.
Codes in this category
This inventory contains only reviewed codes assigned to this subject. Open a code to see its evidence, diagnostic steps and owner-specific actions.
- 2.1.5Destination address is validThe specified recipient mailbox address was found to be valid. This is a success confirmation, not a message rejection.Delivery status2xx · SuccessRecommended actionCheck the full context
- 4.1.1Temporary destination mailbox address problemThe receiving system did not find the specified mailbox during this attempt. Because the code begins with 4, this is a temporary failure: delivery may be retried in a controlled way, but the code alone does not yet establish that the address is permanently invalid.Delivery status4xx · Temporary failureRecommended actionControlled retry
- 4.1.8Temporary sender system address problemThis attempt reported a problem with the system identified by the sender address. Because the code begins with 4, it is a temporary failure: delivery may be retried in a controlled way, but the sender address and system configuration should be checked first.Delivery status4xx · Temporary failureRecommended actionControlled retry
- 5.1.1Recipient mailbox does not existThe specified recipient mailbox does not exist. This is a permanent failure, so do not retry delivery to the same unchanged address.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.1.3Invalid recipient address syntaxThe message was permanently rejected because the recipient mailbox address has invalid syntax. Retrying with the same address will not remove the error.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.1.8Invalid sender system addressThe system identified by the sender address does not exist or cannot accept return mail. Code 5.1.8 is a permanent failure, so do not retry the unchanged send.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.1.10Recipient address points to a null-MX domainThe recipient address is associated with a domain marked by a null MX as not accepting mail. This is a permanent failure, so do not retry delivery to the same unchanged address.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
Wojtek Blazalek
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