On Tue, Dec 15, 2020 at 06:50:59PM +0100, Michael wrote:
> On Tuesday, December 15, 2020 5:57:45 PM CET, Benny Pedersen wrote:
> > Why do you accept your own domain in port 25 as envelope sender?
>
> Because I want to receive my own posts in this or any other mailing list.
Mailing lists as postfix-users change the *envelope* sender, so that
bounces go to the list manager for automated processing, rather than the
original poster. The treatment of "RFC2822.From" (the "From:" message
header) varies by list and may depend on whether the sender's domain
employs DMARC (I am not known for endorsing DMARC).
For many domains it is reasonably safe to reject external mail that
forges the envelope sender domain. This is only an issue with simple
alias expansion when the sender is a member of some informal list
hosted outside his domain.
--
Viktor.
