How to set envelope sender (MAIL FROM) using exim

[Thomas Pircher]

Longman wrote:
> For some reason a system I mail ignores the From address
> and wants to reply to the return-path address despite there being no
> Sender header present and the From being valid and deliverable.

This is IMHO the correct behaviour. You can write whatever you like in the
From: field, but it is harder to lie in the envelope-from, if you are not
the postmaster.

> What solutions are there?

You can override the address on a per-user basis in /etc/email-addresses.
At the moment I don't have access to an exim installation, but I think the
syntax is the same as in /etc/aliases:
user: email at example.com

I'm sure you can address-rewrite the envelope-from to your hearts delight,
but I'm not very experienced in this and can't thus help.

Thomas