Hi Wietse,
Thanks for clearing that out. I read the first part of the manual and thought
it would block if postfix is not the final destination but I didn't really
understand the AND part of the sentence but now I do. So it's not the option I
need. My bad! ;)
Now, to get back to your suggestion.
Can't we use the 'smtpd_sender_restrictions = check_sender_access ...' option
on port 26 only using parameters in master.cf ?
If so, is it possible to use the relay_domains file for the same purpose?
We have "relay_domains = hash:/etc/pmg/domains" in our main.cf
And in /etc/pmg/domains we have domains like this:
domain1.com 1
domain2.com 1
domain3.com 1
domain4.com 1
I'm not sure if it can work with this "1" or does it need to be "OK"?
I'm unsure why there is a "1" but the system we're using is acually proxmox
mail gateway which autogenerates the configuration.
We could create a small script to create a file for sender_access by replacing
the 1 with an OK and writing it to a new file.
But I'm not sure why you suggested we need a different server for inboud and
outbound?
Kind regards,
Sander
----- Original Message -----
From: "Wietse Venema" <wie...@porcupine.org>
To: "postfix-users" <postfix-users@postfix.org>
Sent: Monday, May 13, 2019 1:16:12 PM
Subject: Re: Fwd: Postfix as an outgoing spam filter. How to block email for
unknown senders in local network?
sandermo...@telenet.be:
> After some googling I found that the "reject_unknown_sender_domain"
> option should reject mail if Postfix isn't the sender's domain
> final destination so that sounds good too. I enabled that option
> but it doesn't seem to work?
It works as promised.
reject_unknown_sender_domain
Reject the request when Postfix is not final destination for the
sender address, AND THE MAIL FROM DOMAIN HAS 1) NO DNS MX AND NO
DNS A RECORD, OR 2) A MALFORMED MX RECORD [...]
Have you considered using sender access control on the outbound
SMTP server:
smtpd_sender_restrictions =
check_sender_access inline:{
example.com OK
other.example OK
}
reject
This requires that you have different mail servers for inbound
and outbound SMTP.
Wietse
