Damian Myerscough a écrit :
> Hello,
>
> I had a question regarding forged mail. I wanted to know if it was
> possible for Postfix for
> postfix to check the integrity of incoming emails?
>
> What I mean by this is, if a malicious attacker send an email from
> dam...@hotmail.com is
> there anyway to check that the email came from hotmail.com via a DNS lookup?
>
the simplest thing you can do is something like this:
smtpd_sender_restrictions =
...
check_client_access hash:/etc/postfix/forged_sender_wl
check_sender_access hash:/etc/postfix/forged_sender_bl
== forged_sender_wl
hotmail.com OK
.hotmail.com OK
yahoo.com OK
.yahoo.com OK
...
== forged_sender_bl
hotmail.com REJECT blah blah
yahoo.com REJECT blah blah blah
...
What this do is:
- if mail is coming from whitelisted clients (based on hostname), pass
- else: if sender address is in the map, reject
But if the list in forged_sender_wl is incomplete, you'll reject
legitimate mail. so be careful here.
