Cant send mail due to PTR Records

Question

I just installed sendmail on ubuntu 14.04 lts and configured a new domain. Somehow I must have overseen a config issue, as google mail is rejecting the message. looking at return message it tells me the following:

The original message was received at Tue, 27 Oct 2015 11:59:18 +0100
from staging.www.de.mydomain.com [127.0.0.1]

   ----- The following addresses had permanent fatal errors -----
<[email protected]>
    (reason: 550-5.7.1 [2a01:4f8:212:27c8::2] Our system has detected that this message does)

   ----- Transcript of session follows -----
... while talking to aspmx.l.google.com.:



>>> DATA
<<< 550-5.7.1 [2a01:4f8:212:27c8::2] Our system has detected that this message does
<<< 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and
<<< 550-5.7.1 authentication. Please review
<<< 550-5.7.1  https://support.google.com/mail/?p=ipv6_authentication_error for more
<<< 550 5.7.1 information. y6si29358320wiv.50 - gsmtp
554 5.0.0 Service unavailable

I configured the mx records, but why does the message state that it is received from 127.0.0.1 ?

mail.log has following entry:

 Oct 27 12:49:27 staging sendmail[24866]: t9RBnRJo024866: from=andy, size=72, class=0, nrcpts=1, msgid=<[email protected]>, relay=andy@localhost
 Oct 27 12:49:27 staging sendmail[24866]: t9RBnRJo024866: [email protected], ctladdr=andy (1000/100), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30072, relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection refused by [127.0.0.1]

Any help is greatly appreciated.

Answer 1

Looks like you don't have an appropriate pointer record for your IPv6 address.

This is something your service provider who controls that IP has to add to their DNS records.

The record needs to match the name of your mailserver.

You see the 127.0.0.1 address because the mail was generated on your mail server - so it does indeed come from localhost. That part is completely normal.