Re: Amazon SES

From: Gavin Lambert (boost_at_[hidden])
Date: 2023-05-04 23:24:04

On 5/05/2023 04:40, Sam Darwin wrote:
> Checking original messages locally in my inbox messages, it appears
> mailgun doesn't rewrite the ID. SES rewrites the ID. Not an option to
> disable it. I will open a discussion with mailman and see if they have
> any suggestions.

I think the only solution would be to get SES to stop doing that.  Or to 
stop using SES if it can't.

There's not too much problem if the first message id is rewritten 
(provided both mailman and SES agree on what it is, but that seems hard 
if mailman is earlier in the traffic chain, as appears to be the case).

But for second and subsequent messages in the same thread, replies are 
often sent both to the list and to individual participants, and it's 
critically important that both of these copies have the identical 
message id both so that servers and clients recognise them as duplicates 
(and that one is safe to discard) and so that it doesn't matter which 
copy is replied to next.

Changing the id is just poor netiquette, and it should only be done if 
the incoming email had a malformed id.