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Weblog Archive Cutedge

by: Bernard Teo

Creative Commons License

Copyright © 2003-2012
Bernard Teo
Some Rights Reserved.

Wed 13 Oct 2004

ISP blocks port 25? No problem

Category : Technology/Port25.txt

Ronnie Teo found the solution to a problem that quite a few people have encountered - the case of an ISP blocking port 25, the default port that mail servers use to contact each other. This is what he says :

Just to share with you some good news. My mail server is up again. Finally. The mailhop relay service offered by Dyndns was the solution. This was what I had to do:

1. In Custom Postfix Settings (in Postfix Enabler, below), two parameters were added: soft_bounce=no, and, unknown_local_recipient_reject_code=550

2. On the Dyndns website, I chose an alternate port on offer from a list including 24, 25, 587, 2525, 10025 and 52525. I chose 587.

3. Then I forwarded this port on my Linksys router.

4. Lastly, I went into file to add a line to make postfix listen on the alternate port 587 (instead of just SMTP 25 port)

That's it. The last thing is to wait. I thought it didnt work initally because nothing happened. Then this morning when I came to the station, all the incoming mail sent over the the last 4 days were there (including the one from Hai Hwee); all automatically retrieved by Spamfire.

Now I am happy and relieved and I have you to thank for it. So, thanks again.

Thanks for sharing the solution, Ronnie. For point 4, the line to add in the /etc/postfix/ file is :

587 inet n - n - - smtpd

There is already a line that says :

smtp inet n - n - - smtpd

so you add the 587 line to it.

As Ronnie mentioned, you can chooose to use 24, 25, 587, 2525, 10025 or 52525, if your ISP blocks more ports than port 25.

I'm thinking of making this even easier to do by incorporating it into the Postfix Enabler interface - probably the version that I'm preparing for Tiger. But, for the moment, this looks easy enough to do, manually.

So, there. I ought to look into all my mail about Postfix Enabler and do an FAQ. Oughta. Shoulda. Gotta find the time.

Posted at 4:22AM UTC | permalink

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