Michael Monnerie:
> I've just had a very strange bug which cost me an hour to find.
>
> mailserver: postfix-2.5.1-28.5
>
> On the mailserver, I should receive mail from 212.69.162.205.
>
> # dig -x 212.69.162.205
> showed me a correct, existing PTR:
> 205.192-28.162.69.212.in-addr.arpa. 3600 IN PTR protegate5.zmi.at.
>
> Just the forward request doesn't fit the IP:
> # dig +short protegate5.zmi.at
> 212.69.164.56
>
> and postfix refused to take the e-mail with this message:
> 450 4.7.1 Client host rejected: cannot find your hostname,
> [212.69.162.205]
>
> The log text is not correct, it should say "your PTR 212.69.162.205
You are looking at the wrong information. As a matter of principle,
Postfix does not give full details to SMTP clients.
Instead, you should look at the warnings and other information that
Postfix logs in the maillog file. These warning messages explain
exactly why the name lookup does not resolve as it should.
Here are some examples from my own logfile:
This was logged when a reverse hostname did not resolve at all:
Aug 26 00:15:04 spike postfix/smtpd[13144]: warning: 190.22.83.47:
hostname 47-83-22-190.adsl.tie.cl verification failed:
Non-recoverable failure in name resolution
And this was logged when a reverse hostname resolved to the wrong IP
address:
Aug 26 00:26:12 spike postfix/smtpd[13393]: warning: 61.135.132.106:
address not listed for hostname relay2nd.mail.sohu.com
Wietse
