On 04/29/2011 08:02 AM, Rich Wales wrote:
I have a choice between sending out mail directly from my server to
a message's destination (MX host), or sending mail via my domain's
web hosting service. (Yes, my ISP really does allow me to connect
to any SMTP server, and I have a static IP address that isn't currently
listed in the Spamhaus PBL or other realtime blacklists.)
What I would like to do is to try first to send any outbound mail
directly to the destination -- but if that fails due to a blacklist
problem (i.e., if the destination doesn't like my mail server), then
I want to fall back to sending via my web hosting service's smarthost.
If what happens - the destination REJECTs your message ?
Postfix will not try another route if that happens; any 5xx status is
final, and the message will be bounced.
You can set soft_bounce to retry 5xx errors, but this has a much wider
impact than just what you want to achieve.
The reason I don't want to just send everything out via the smarthost
is that my web hosting service's servers occasionally get blacklisted
because of spam generated by other customers (not me). Hopefully I
can avoid being penalized for someone else's misdeeds by sending out
mail directly from my server to the destination. But I've run into
one ISP (AT&T) which has somehow gotten my local server's IP address
in its blacklist -- and if I'm unable to convince them to delist me,
or if this sort of thing happens again sometime, I want Postfix to
automatically try "Plan B".
In general, is there any way to do what I want?
Certainly:
- contact AT&T to get your IP unlisted
- make sure your sending machine has proper forward confirmed reverse DNS:
http://en.wikipedia.org/wiki/Forward_Confirmed_reverse_DNS
Unless you're really sending spam or other large amounts of dubious
content, a mail server in a proper datacenter (i.e. with a
non-residential IP) with proper fcrDNS isn't blacklisted that easily.
--
J.
