Match final replies to successful RCPT commands
03After the DATA terminator, LMTP returns one final reply per previously successful RCPT command, in that command order. Rejected recipients do not occupy a reply slot.
Separate reply excerpt: 250-first line followed by 250 final line is one multiline positive reply, corresponding to a single successful RCPT command. It is not two recipients.
Source for this drawing: RFC 2033 · Read RFC section 4.2 ↗
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Mail transport moves a message between servers. The message format describes its contents. Authentication adds checks; it does not make every message safe.
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These pictures are analogies to help you learn. The linked RFC explains the actual rules.
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Count command occurrences, not distinct email addresses or reply lines.
- The final dot changes the reply cardinality: one reply for each successful RCPT command in order. A previously rejected RCPT has no post-content reply slot.
- Two successful RCPT commands for the same address still require two replies. A multiline reply is one reply for one command occurrence.
- A positive final completion means the server accepts responsibility for delivering or relaying to that recipient. It MUST NOT lose the message for frivolous reasons such as predictable resource shortage or a later crash.
The first two scenes adapt the RFC example to fictional example.org addresses: Pat accepted, Jones rejected, Green accepted; final 250 and 452 correspond only to Pat and Green. Duplicate-recipient and multiline scenes are separate cases. Positive acceptance does not mean a person has read the message.
Read the RFC section ↗