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Re: comcast, port 25, and postfix?

Tom Horsley <tom horsley att net> writes:
> I just got mail from comcast telling me they have blocked
> port 25 on my cablemodem due to possible abuse (I don't
> really care if they do this - I'm not using port 25).

Local port 25 or remote port 25?

I'm maintaining a friend's Fedora system remotely and have noticed that
AT&T blocks remote port 25 on their DSL installs.  I had to open up an
alternate incoming mail port here (smtps) and configure the remote end
to use smtps just to get the nightly cron messages from the remote box.

> Just curious: Anyone know if postfix will try to talk port
> 25 for any reason if I've got it configured to send
> via the relay? Or is this just comcast trying to sound
> like they have a good reason to do what they always
> wanted to do and block smtp :-)? Or are there maybe
> obscure kerneloops or smolt or bugbuddy things trying
> to talk port 25 directly sometimes?

I guess it depends on how you configured your postfix. ;-) There are
ways to do fallback smarthost setups, but that is more work.  The
obvious setup with something like the following should only send to the
requested host at the requested port number.

relayhost = [relayhost.example.com]:465

I assume you did comment out the smtp line in master.cf or otherwise
prevented outsiders from connecting to your server.

Wolfgang S. Rupprecht              http://www.full-steam.org/  (ipv6-only)
         You may need to config 6to4 to see the above pages.

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