postfix-users March 2010 archive
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postfix-users: Re: retry with ssmtp if smtp delivery fails

Re: retry with ssmtp if smtp delivery fails

From: Victor Duchovni <Victor.Duchovni_at_nospam>
Date: Fri Mar 05 2010 - 22:07:25 GMT
To: Roel van Meer <rolek@bokxing.nl>

On Fri, Mar 05, 2010 at 12:05:05PM +0100, Roel van Meer wrote:

> Hi list,
>
> Does anyone know if it is possible to configure postfix in such a way that
> it tries to deliver mail via ssmtp if delivery via smtp fails?
>
> Background: We're operating a backup relayhost for a number of customers.
> Their primary mail server is usually connected via adsl or cable. We're
> seeing that some providers block incoming smtp, but not (yet) ssmtp. I
> would like our relayhost to first try delivery via smtp, and if that fails
> (because it could not connect) to retry via ssmtp.

This would be wrong. The "ssmtp" service, if it existed, is generally
for submission, not inbound MX delivery, and almost always requires
authentication, which you will not be able to provide. You would get
random rejection of your email if you guess random ports on the peer
system to deliver to.

The right answer is to negotiate the right port with each downstream client,
and use a transport table.

-- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note.