Re: override regular transport?

On 23/05/05 00:43 -0700, email builder wrote:
<snip>
> I also need user-configurable filters with possible delivery to more than
> just a quarantine directory, which only something like procmail or Maildrop
> used as LDA will give me as far as I know. If there was a way to kick off
> Maildrop as a content filter, um, maybe that'd work, um... maybe? Seems very
> strange and maybe will slow postfix a lot.
>
> > I hope this simplifies the problem statement slightly.
>
> It's close, but I need a little more than just a firewall for spam and virii,
> but I am *certainly* interested to hear how you think it would be better
> done. If I were to JUST implement a "firewall" as you suggest, how is that
> best done? Is that something that amavis (wrapped around SA/clamav) can do?
> Can amavis redirect those quarantined mails to *per-user* spam and virus
> folders?
>
Yes. See the address extensions which amavisd-new can add.

> > I would use a content_filter which accept mail via SMTP, filters
> > according to whatever rules are specified, rewrites the envelop
> > recipients to ${user}+${extension}@${myhostname}.${original_doma in}
> > and reinjects via smtpd. Unclassified/unfiltered mail is reinjected
> > unchanged.
> > $myhostname.$original_domain is in virtual_mailbox_maps (or
> > mydestination) as needed.
> > $original_domain is in relay_domains only.
>
> I see. Re-written mails are the ones that are stopped at the server, NOT the
> ones getting relayed. I assume amavis has functionality to do that kind of
> envelope recipient re-writing?
>
Yes.

> > I hope this helps you in figuring out a solution.
>
> Yes and no. I CERTAINLY appreciate your help. This is a good second
> solution for us, but we'd also like user-configurable filters too...
>
Here is what I would do:
Start with amavisd-new (and rip out code), or use Todd Bennett's SMTP
proxy framework and add code to do the following:

1> Look up a list of keywords from a database of some sort, using the
recipient address as a key.
2> For each keyword, do a defined action.
3> For each action, either rewrite the envelop sender, or add a special
header to the message, or both.
4> Relay the message back to Postfix.
5> If the envelop sender is rewritten to a host in mydestination, you
can use maildrop/procmail filters based on your custom header to filter
the mail to appropriate mailboxes. If you only need delivery to one
folder, just use address extensions and let Postfix/local handle mail
delivery.

Devdas Bhagat