Postfix relaying problem

tsyuoi · 10-17-2007, 01:21 PM

Hi!

I have a problem when sending a mail to something@siol.net (siol.net is my ISP)
I have followed instructions in this howto:
http://workaround.org/articles/ispmail-etch/

My /var/log/mail.log file with error of this:

Code:

Oct 17 20:08:47 streznik postfix/smtpd[11046]: connect from localhost.localdomain[127.0.0.1]
Oct 17 20:08:48 streznik postfix/smtpd[11046]: 1E2301F337A: client=localhost.localdomain[127.0.0.1]
Oct 17 20:08:48 streznik postfix/cleanup[11049]: 1E2301F337A: message-id=<64277.195.210.202.46.1192644528.squirrel@lokalni.net>
Oct 17 20:08:48 streznik postfix/smtpd[11046]: disconnect from localhost.localdomain[127.0.0.1]
Oct 17 20:08:48 streznik postfix/qmgr[3328]: 1E2301F337A: from=<rakar@fitness-slovenia.info>, size=746, nrcpt=1 (queue active)
Oct 17 20:08:48 streznik postfix/smtp[11051]: 1E2301F337A: host mailhub.siol.net[193.189.160.212] refused to talk to me: 421 Service not available
Oct 17 20:08:48 streznik postfix/smtp[11051]: 1E2301F337A: host mailhub.siol.net[193.189.160.25] refused to talk to me: 421 Service not available
Oct 17 20:08:48 streznik postfix/smtp[11051]: 1E2301F337A: to=<pierce@siol.com>, relay=mailhub.siol.net[193.189.160.211]:25, delay=0.72, delays=0.42/0.03/0.28/0, dsn=4.0.0, status=deferred (host mailhub.siol.net[193.189.160.211] refused to talk to me: 421 Service not available)

I send a mail to my ISP asking what could be wrong, because my ip resolves to my domain name and vice versa. And I got a reply explaining me that this error is shown because I send mail throu their server mailhub.siol.net and that if I have my own server I should send mesages throu it. Or else this relaying thing has to be configured.

I read something about this on postfix sites but I kinda don't understand. Could someone explain in some simple way what this means, and give me a hint in which direction I have to search to repair this error?

Thank you,
Matic

WindowBreaker · 10-17-2007, 05:35 PM

Are you trying to send all outgoing email thru your ISP's mail server? That would be a good idea, as running a home mail server is likely to get spam-filtered a lot, based on dynamic ip's, and no reverse DNS mapping.

To do so, set the relayhost in main.cf. You can do that by running as root:

Code:

postconf -e "relayhost = smtp:[isps.mail.server.name]"

The restart postfix by:

Code:

postfix reload

If this doesn't work, your ISP's SMTP server may require authentication. If that's the case, let me know and I'll show you how to set it properly as a SASL client.

tsyuoi · 10-18-2007, 07:51 AM

Thank you for reply.
No I am not sending all mesagaes throu ISPs server. I would like to send mail from my own server. How can I set that?

Matic

WindowBreaker · 10-18-2007, 01:15 PM

In your log file that you posted, we are only interested in the 'smtp:' lines, as that is the smtp client, and we are dealing with problem sending mail.
ie:

Quote:

Oct 17 20:08:48 streznik postfix/smtp[11051]: 1E2301F337A: host mailhub.siol.net[193.189.160.212] refused to talk to me: 421 Service not available

If you look at the line above, your smtp client (postfix) is telling you that mailhub.siol.net is refusing to talk to it. In other words, it's not a firewall issue, it's just that mailhub.siol.net is refusing to even TALK to your mail server. Why? That's a good question. Probably because that mail server has checks in place to reduce spam. Checks, such as 'if client has a dynamic ip, don't talk to it', and 'if client does not have a valid reverse dns mapping, don't talk to it'. In some cases, the server that rejects you will indicate why they rejected you. That's not the case here. They may not want to divulge why, to delay spammers in bypassing their checks.

If it were me, try sending mail to 5 or 6 different domains. See if any of them go thru. Then you'll know you're not misconfigured, it's just that certain mail servers won't talk to yours.

From there, you can focus on the 'smtp:' entries in the logs to see if you get a rejection code, or something similar.

One thing I noticed, is that you got rejected with a 4xx code. And, it specifically stated 'service not available'. I think that mail server is either misconfigured, or is having issues. The reason is that 4xx codes are temporary rejection codes, that are in essense saying, try again in a few minutes, cuz I'm having a [hopefully] temporary problem at the moment.

Trying to send to other domains should help you pinpoint the issues.