- Reindl Harald h.reindl@thelounge.net:
Am 25.06.2013 15:28, schrieb Timo Sirainen:
Also there are several potential problems.. Like if there are duplicate Message-ID: headers, but the body is different, should that be a duplicate?
the answer is simply *yes* because there must not be the same Message-ID's for different messages because the words "single unique message identifier" are pretty clear
RFC2822
Though optional, every message SHOULD have a "Message-ID:" field. Furthermore, reply messages SHOULD have "In-Reply-To:" and "References:" fields as appropriate, as described below.
The "Message-ID:" field contains a single unique message identifier. The "References:" and "In-Reply-To:" field each contain one or more unique message identifiers, optionally separated by CFWS.
these days "every message SHOULD have a Message-ID:" is outdated
we started many years ago to block *any* message missing the header because every sane SMTP implementation adds it if it was missing from the client and so only broken implementations which are mostly spammers would be affected
We had one funny occurance of that particular corner-case:
- Somebody sent us an email
- the user's account autoreplied on the eveing upon receipt (out of office) That autoreply was sent with a message-id A
- next morning, the user read the mail, and composed a personal reply
- that reply was discarded by the recipient's mailserver, since it had the same message-id A (dunno why that happened, but it did!) as the auto-reply the evening before.
That took me a while to discover.
-- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebrandt@charite.de | http://www.charite.de