550-5.7.26 Unauthenticated email from gmail.com is not accepted due to domain's 550-5.7.26 DMARC policy.

[BiteMyElbow]

Redirected mails are sometimes bounced from Gmail.

We have PMG installed if front of Exchange 2013. All income and otcome mail goes through PMG as it is our edge mail server.

We have a simple forward rule, "if the mail arrives at user's mailbox user1@ourcorporatedomain.com send a copy to user1privatemaillbox@gmail.com".

And it works BUT NOT EVERY TIME:


Bounced messages are similar:

Nov 17 12:59:38 PMG postfix/smtpd[466447]: connect from exchange2013.localdomain.local[172.30.21.112]
Nov 17 12:59:39 PMG postfix/smtpd[466447]: 01DBA161AB3: client exchange2013.localdomain.local[172.30.21.112]
Nov 17 12:59:39 PMG postfix/cleanup[466358]: 01DBA161AB3: message-id=<CALq2_DYqJU-3=gjX9-Dr2VgR=AgQUvbmhCwhqQQtT7d8mv64mg@mail.gmail.com>
Nov 17 12:59:39 PMG postfix/qmgr[829]: 01DBA161AB3: from=<user1@ourcorporatedomain.com>, size=119516, nrcpt=1 (queue active)
Nov 17 12:59:39 PMG postfix/smtpd[466447]: disconnect from excnahge2013.localdomain.local[172.30.21.112] ehlo=2 starttls=1 mail=1 rcpt=1 bdat=1 quit=1 commands=7
Nov 17 12:59:39 PMG pmg-smtp-filter[466486]: 161ABA6557398B0ECD9: new mail message-id=<CALq2_DYqJU-3=gjX9-Dr2VgR=AgQUvbmhCwhqQQtT7d8mv64mg@mail.gmail.com>#012
Nov 17 12:59:39 PMG postfix/smtpd[466340]: connect from localhost.localdomain[127.0.0.1]
Nov 17 12:59:39 PMG postfix/smtpd[466340]: 24B5A161ABF: client=localhost.localdomain[127.0.0.1], orig_client=exchange2013.localdomain.local[172.30.21.112]
Nov 17 12:59:39 PMG postfix/cleanup[466335]: 24B5A161ABF: message-id=<CALq2_DYqJU-3=gjX9-Dr2VgR=AgQUvbmhCwhqQQtT7d8mv64mg@mail.gmail.com>
Nov 17 12:59:39 PMG postfix/cleanup[466335]: 24B5A161ABF: resent-message-id=<20231117095939.24B5A161ABF@PMG.localdomain.local>
Nov 17 12:59:39 PMG postfix/qmgr[829]: 24B5A161ABF: from=<user1@ourcorporatedomain.com>, size=118723, nrcpt=1 (queue active)
Nov 17 12:59:39 PMG postfix/smtpd[466340]: disconnect from localhost.localdomain[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 commands=5
Nov 17 12:59:39 PMG pmg-smtp-filter[466486]: 161ABA6557398B0ECD9: accept mail to <user1privatemaillbox@gmail.com> (24B5A161ABF) (rule: default-accept)
Nov 17 12:59:39 PMG pmg-smtp-filter[466486]: 161ABA6557398B0ECD9: processing time: 0.142 seconds (0, 0.049, 0)
Nov 17 12:59:39 PMG postfix/lmtp[466336]: 01DBA161AB3: to=<user1privatemaillbox@gmail.com>, relay=127.0.0.1[127.0.0.1]:10023, delay=0.2, delays=0.01/0/0.04/0.15, dsn=2.5.0, status=sent (250 2.5.0 OK (161ABA6557398B0ECD9))
Nov 17 12:59:39 PMG postfix/qmgr[829]: 01DBA161AB3: removed
Nov 17 12:59:39 PMG postfix/smtp[466458]: 24B5A161ABF: to=<user1privatemaillbox@gmail.com>, relay=gmail-smtp-in.l.google.com[108.177.14.27]:25, delay=0.5, delays=0.05/0/0.08/0.37, dsn=5.7.26, status=bounced (host gmail-smtp-in.l.google.com[108.177.14.27] said: 550-5.7.26 Unauthenticated email from gmail.com is not accepted due to domain's 550-5.7.26 DMARC policy. Please contact the administrator of gmail.com domain 550-5.7.26 if this was a legitimate mail. Please visit 550-5.7.26 https://support.google.com/mail/answer/2451690 to learn about the 550 5.7.26 DMARC initiative. u18-20020a2e1412000000b002c01ec81656si518844ljd.149 - gsmtp (in reply to end of DATA command))
Nov 17 12:59:39 PMG postfix/qmgr[829]: 24B5A161ABF: removed

Both SFP and DMARC records are configured correctly.
SPF: v=spf1 a mx -all
DMARC: v=DMARC1;p=quarantine;rua=mailto:soa@ourcorporatedomain.com;ruf=mailto:soa@ourcorporatedomain.com;fo=1

I search for resolution on PMG forum but was unable to find one.

How can we fix it?

 

[BiteMyElbow]

Any help?

 

[dcsapak]

hi,

could it be that the mails not working have a 'from' header that includes a gmail.com address? if yes then this is the point of dmarc, since
gmail says: 'from gmail only with valid dmarc' but you don't have a valid dmarc header for the from (assuming it contains gmail)

if not, can you post the header of such a mail?