From
Subject
Time (UTC)
MAILER-DAEMON@emkei.cz
Undelivered Mail Returned to Sender
2016-09-19 12:17:34
To:
From: MAILER-DAEMON@emkei.cz (sender info)
Subject:

Undelivered Mail Returned to Sender


Received: 2016-09-19 12:17:34

This is the mail system at host emkei.cz. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system : host gmail-smtp-in.l.google.com[2a00:1450:4013:c00::1b] said: 550-5.7.1 [2a01:5e0:36:5001::20] 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=IPv6AuthError for more information 550 5.7.1 . f185si22897048wma.105 - gsmtp (in reply to end of DATA command)