Message content and format
Message content, media, conversion, encoding, and structural format problems.
This category covers seven reviewed codes concerning content conversion and availability, UTF-8 encoding, and restrictions on address and SMTP reply formats. Two class-2 codes record success: 2.6.4 means delivery after a conversion that lost data, while 2.6.8 reports a result in which showing the mailbox name would require a UTF-8 reply that the client does not permit. The remaining class-5 codes describe permanent failures: an unsupported required conversion, unavailable content that could not be fetched, a non-ASCII address that is not permitted, the same UTF-8 reply conflict, and inability to transfer a message with a UTF-8 header after DATA completes. The complete code is therefore essential for distinguishing a warning attached to successful delivery from a permanent rejection.
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.
- 2.6.4Conversion with data loss performedThe message was delivered, but delivery required a conversion in which some data was lost. This is a successful-result warning, not a rejection.Delivery status2xx · SuccessRecommended actionCheck the full context
- 2.6.8Required UTF-8 reply not permitted by the SMTP clientA reply needed to show the mailbox name would have to contain a UTF-8 string, but the SMTP client does not permit that form of reply. Code 2.6.8 reports this as a success status, not a rejection.Delivery status2xx · SuccessRecommended actionCheck the full context
- 5.6.3Required conversion is not supportedThe message failed permanently because forwarding it required a content conversion that a host in the path could not practically perform. Do not retry the same unchanged attempt.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.6.6Message content is not availableThe attempt failed permanently because the message content could not be fetched from a remote system. Do not retry the same unchanged attempt.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.6.7Non-ASCII address is not permitted for the sender or recipientA system permanently rejected a MAIL or RCPT command because the sender or recipient address contained non-ASCII characters that were not permitted in that context. Do not retry the same unchanged attempt.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.6.8Required UTF-8 reply not permitted by the SMTP clientThe attempt failed permanently because showing the mailbox name required a reply containing a UTF-8 string, but the SMTP client did not permit that form of reply. Do not retry the same unchanged attempt.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
- 5.6.9Message with a UTF-8 header cannot be transferredThe message was permanently rejected after its data had been transmitted because it could not be transferred with its UTF-8 header to one or more recipients. Do not retry the same unchanged attempt.Delivery status5xx · Permanent failureRecommended actionDo not retry unchanged
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