Feature wishlist: Allow to hide client IP/host in submission service

[Sebastian Krause]

Timo Sirainen <timo at sirainen.com> wrote:
> Yeah, it would be useful to hide the client's IP and do it by
> default. Actually I think there shouldn't even be an option to not
> hide it. Or would it be better or worse to just not have the
> Received header added at all?

I don't think it's a good idea to just hide the Received header
completely because it contains useful information to track down mail
problems:

Received: from client.example.com ([1.2.3.4])
    by mail.example.com with ESMTPSA
    id PBjFKTKxZl3AEQAA1ctoJQ
    (envelope-from <sebastian at realpath.org>)
    for <sebastian at realpath.org>; Wed, 28 Aug 2019 18:52:02 +0200

The third line contains the "id" that also shows up in the Dovecot
logs and might be the quickest way to track down users with abusive
behavior (e.g. spammers).

If a configuration option is too much, I think anonymizing by
default is the next best approach, with the first line of the header
being something like this:

Received: from submission ([127.0.0.1])