Mechiel Lukkien 9e7d6b85b7 queue: deliver to multiple recipients in a single smtp transaction ... transferring the data only once. we only do this when the recipient domains are the same. when queuing, we now take care to set the same NextAttempt timestamp, so queued messages are actually eligable for combined delivery. this adds a DeliverMultiple to the smtp client. for pipelined requests, it will send all RCPT TO (and MAIL and DATA) in one go, and handles the various responses and error conditions, returning either an overal error, or per recipient smtp responses. the results of the smtp LIMITS extension are also available in the smtp client now. this also takes the "LIMITS RCPTMAX" smtp extension into account: if the server only accepts a single recipient, we won't send multiple. if a server doesn't announce a RCPTMAX limit, but still has one (like mox does for non-spf-verified transactions), we'll recognize code 452 and 552 (for historic reasons) as temporary error, and try again in a separate transaction immediately after. we don't yet implement "LIMITS MAILMAX", doesn't seem likely in practice.		2024-03-07 10:07:53 +01:00
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send.go	queue: deliver to multiple recipients in a single smtp transaction	2024-03-07 10:07:53 +01:00
send_test.go	queue: implement adding a message to the queue that gets sent to multiple recipients	2024-03-05 20:10:28 +01:00