From: berny (berny.mailseznam.cz)
Date: Thu Jul 12 2007 - 08:54:26 CDT

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> ------------ Pùvodní zpráva ------------
> Od: <wietseporcupine.org>
> Pøedmìt: Re: problem with rejected client
> Datum: 12.7.2007 15:25:15
> ----------------------------------------
> berny:
> > I have configured " reject_unknown_client" in "smtpd_client_restrictions".
> > I get this error from some client:
> >
> > 450 Client host rejected: cannot find your hostname
> >
> > But the IP address can be resolved to name and name can be resolved
> > to IP address.
> > Do you have any hint?
>
> Wietse:
> > > See:
> > >
> > > http://www.postfix.org/postconf.5.html#reject_unknown_client_hostname
> >
> > yes, I've seen it
> >
> > > reject_unknown_client_hostname (with Postfix < 2.3: reject_unknown_client)
> > > Reject the request when 1) the client IP address->name mapping
> > > fails, 2) the name->address mapping fails, or 3) the name->address
> > > mapping does not match the client IP address. This is a stronger
> > > restriction than the reject_unknown_reverse_client_hostname
> > > feature, which triggers only under condition 1) above.
> >
> > 1) client IP address is the address of connecting MTA
> > the resolving the name from IP is OK
>
> Thus, step #1 succeeds: the client IP address->name lookup (the PTR
> record in the DNS).
>
> > 2) where postfix takes the name? form helo command?
> > when I resolve name in helo command it's the client IP address
>
> From step #1: the client IP address->name lookup.
>
> In your case, either step #2 fails (name->address lookup), or step
> #3 fails (name->address does not match client IP address).

yes, you're right!
the other side has changed mailserver,but not DNS records in the same time, but later
and when I was solving it, they corret the DNS records but I red from old log file and didn't look for new mail logs.

thx

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