Reinject to Postfix, or just send on to LMTP?

[/dev/rob0]

On Sun, May 26, 2013 at 07:11:20PM +0200, Ralf Hildebrandt wrote:
> * /dev/rob0 <rob0 at gmx.co.uk>:
> > Please forgive what might be a too-basic question. I'm setting up 
> > a new system with Postfix/virtual delivering to Dovecot LMTP. I'm 
> > not quite understanding if there is any benefit to this design:
> 
> > 	Postfix -> Amavisd-new -> Postfix/reinject -> Dovecot LMTP
> 
> The first postfix only checks for unknown users
> Postfix/reinject does alias expansion/virtual_aliasing
> 
> If you don't need "alias expansion/virtual_aliasing", denn 
> 
> > as opposed to this:
> > 	Postfix -> Amavisd-new -> Dovecot LMTP
> 
> is for you.

Oh, good point. Thanks. I need to plan for how a virtually aliased 
address would be handled. It's quite possible that something could 
come in via the MX port but end up going out to the Internet. That
was what I missed.

On further thought I think it will work well enough. I won't need 
receive_override_options (as you mentioned in the other post.)

In virtual_alias_maps (example.com being my virtual mailbox domain, 
remote.tld being external):

user at example.com	user at example.com,user at remote.tld

Postfix splits this into two deliveries. One goes to amavisd via 
virtual_transport. Amavisd filters this as incoming and passes 
whatever remains of it to Dovecot LMTP. The other one hits my 
wildcard FILTER rule and goes to amavisd's other port as outbound 
mail.

This raises a point that maybe I'll want another policy bank with 
stricter rules (lower spam thresholds in particular) for such 
departing mail which originated externally.

I guess I'll be filtering submission mail destined to the 
virtual_transport twice, but that doesn't bother me. Better too much 
scrutiny applied than too little.

Off the subject, but I'm wondering: will amavisd support the new 
multiple recipient_delimiter feature that Postfix 2.11 will have?
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