[CentOS] Replacing sendmail with postfix

[Peter]

On 21/09/19 9:07 AM, Chris Adams wrote:
> Once upon a time, Kenneth Porter <shiva at sewingwitch.com> said:
>> Perfect. I think the only other significant customizations I have
>> are lines to use the MIMEDefang and OpenDKIM milters. When last I
>> looked into migrating, I recall that Postfix handled milters just
>> fine.
> 
> Milters work a little different under postfix IIRC... I haven't tried
> them (which is a little sad, since I think I may have been the first
> person to write a sendmail milter :) ).

Postfix has excellent milter support, it may not work exactly the same 
as they do in sendmail but they are designed to be fully compatible with 
sendmail milters.  Also I believe that nowadays milters are written just 
as much to be support postfix as sendmail, if not moreso:

http://www.postfix.org/MILTER_README.html

>> Meanwhile, I'd considered replacing procmail with the Dovecot
>> delivery program to get access to Sieve filtering but didn't see how
>> to easily invoke SpamAssassin as I do now in /etc/procmailrc. Is
>> Procmail still the default delivery agent in RHEL8?

I would recommend dovecot lmtp over dovecot lda.

> Postfix can use dovecot lmtp or procmail (I don't remember which is default).

Postfix can use just about any delivery agent.  The default in postfix 
is to use its own local(8) and virtual(8) delivery agents.  That said, 
these delivery agents are very limited in comparison to dovecot lmtp or 
procmail.

> IIRC sieve may not provide external scripting for security reasons.

I'm pretty sure it does via managesieve.

> I use spamassassin via amavisd-new, with messages going postfix ->
> amavisd -> second postfix (all via SMTP).

This is a good setup, but you may find that you can eliminate the second 
postfix step there and go postfix -> amavisd-new -> dovecot lmtp. 
Unless you need additional processing specifically from postfix after 
amavisd-new, that is.


Peter