On 2023-02-10, Michael Peddemors <michael@linuxmagic.com> wrote:
TOP POSTING for clarity
I think this is getting off topic for the dovecot list. Vacation messaging is a complex topic, and for the record it does seem that the way they are doing vacation messages could use improvement.
This should NOT be sent as a BOUNCE <>, and it should NOT come from MAILER-DAEMON, as it is actually from the person with the vacation message.
Pigeonhole is following RFC 3834 which sees it differently, in particular the RFC tries to avoid anything which might trigger loops.
Since in most cases it is not appropriate to respond toan automatic response, and the responder is not interested in delivery status messages, a MAIL FROM address of <> MAY be used for this purpose. A MAIL FROM address which is specifically chosen for the purpose of sending automatic responses, and which will not automatically respond to any message sent to it, MAY be used instead of <>.
It also should NOT have a precedence header of BULK.
A response MAY include a Precedence field [I4.RFC2076] in order to discourage responses from some kinds of responders which predate this specification. The field-body of the Precedence field MAY consist of the text "junk", "list", "bulk", or other text deemed appropriate by the responder. Because the Precedence field is non-standard and its interpretation varies widely, the use of Precedence is not specifically recommended by this specification, nor does this specification recommend any particular value for that field.
The actual problem is that Pigeonhole responds to to=<010301863b0211fe-9416f5b2-7e18-4c03-a5e5-2204dd7946f8-000000@sa-east-1.amazonses.com> instead of to=<rolf@example.de>.
Exactly as it should:
In general, automatic responses SHOULD be sent to the Return-Path field if generated after delivery. If the response is generated prior to delivery, the response SHOULD be sent to the reverse-path from the SMTP MAIL FROM command, or (in a non-SMTP system) to the envelope return address which serves as the destination for non- delivery reports.