> On Aug 28, 2009, at 5:50 PM, Noel Jones wrote:
> > Mail from yahoo.com is now rejected with:
> > Aug 28 16:24:05 mgate2 postfix/smtpd: NOQUEUE: reject: RCPT
> > from web34202.mail.mud.yahoo.com[22.214.171.124]: 554 5.7.1
> > <web34202.mail.mud.yahoo.com>: Helo command rejected: Malformed DNS
> > server reply; from=<yuser@...> to=<user@...> proto=SMTP
> > helo=<web34202.mail.mud.yahoo.com>
> > If we look up the helo name, we see:
> > # host web34202.mail.mud.yahoo.com
> > web34202.mail.mud.yahoo.com has address 126.96.36.199
> > web34202.mail.mud.yahoo.com mail is handled by 0 .
> > Apparently the bogus MX record triggers the reject. It also looks
> > as if all of Yahoo!'s mail servers are configured with a similar MX
> > record.
> My guess is that this record is malformed because 0 is not a valid IP
> address. Sounds like Yahoo has some issues to work out.
The "0" indicates the MX host preference, and "." indicates the MX
host name. An empty string is not a valid hostname by my reading
of RFCs, and therefore Postfix complains about it.
I have backed out the changes that triggered the false rejects
discussed in this thread, and have issued new Postfix releases.