Outlook email delivery issues.

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michaelmurfy

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#236228 24-May-2018 14:16

Hi all,

I'm having some problems with an email server I manage delivering emails to Outlook / Hotmail and am trying to work out what is going on here. The email server is on the domains SPF list (and passes SPF) but doesn't have DKIM / DMARC configured.

I see the server "delivers" the mail successfully:

May 24 13:59:20 ironhide postfix/smtp[21046]: 93F7C1FCA8: to=<*****@outlook.com>, relay=outlook-com.olc.protection.outlook.com[104.47.45.33]:25, delay=1.3, delays=0.01/0.01/0.47/0.87, dsn=2.6.0, status=sent (250 2.6.0 <d6acdce3be901ede7569bc0b7e6883d8@domain.com> [InternalId=6425271132094, Hostname=CO1NAM04HT227.eop-NAM04.prod.protection.outlook.com] 7427 bytes in 0.408, 17.736 KB/sec Queued mail for delivery) May 24 13:59:20 ironhide postfix/qmgr[3425]: 93F7C1FCA8: removed

However, this email never comes through to the users inbox or junk folder. It is a little harder to diagnose since the email is accepted for delivery and removed from the postfix queue on the server.

Every other domain is totally fine (Gmail, Yahoo etc) and accepts mail. I've checked both the IPv4 + IPv6 addresses on the server but it is not blacklisted anywhere.

Any ideas? Also, since this email server handles 1000's of emails per day it is rather difficult / expensive to use a smarthost before anyone suggests it.

freitasm

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#2021882 24-May-2018 14:58

You say it passes SPF and that the server itself doesn't have DKIM - but does the domain have DKIM/DMARC records?

These links are referral codes

michaelmurfy

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#2021910 24-May-2018 15:45

freitasm:

You say it passes SPF and that the server itself doesn't have DKIM - but does the domain have DKIM/DMARC records?

Yes, the domain has DKIM records for other services sending mail but not for this server. I've just been lazy, will set up DKIM tonight on this server.

I also found the IPv6 address of this server wasn't on the SPF record. Postfix however isn't using IPv6 but added anyway.

Still annoying it can send mail to everything except Microsoft hosted services...

wazzageek

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#2022075 24-May-2018 19:56

I have two Office365 accounts that I have full access to if you want to send me an email and I can check the "mail flow" in the exchange console? That might help shed some light on it? PM me if you want to try that.

Cheers!

michaelmurfy

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#2022076 24-May-2018 19:57

Hmm - no show. Have set up DKIM on the server and DMARC on the domain and emails are sent successfully to everything except outlook.com, live.com and hotmail.com. Showing delivered on the server with no errors.

I've also avoided my Postfix configuration by sending email directly to Outlook using swaks - shows successfully sent:

<- 250 2.6.0 <20180524193257.025235@hostname> [InternalId=6442450976892, Hostname=DM3NAM03HT004.eop-NAM03.prod.protection.outlook.com] 5943 bytes in 0.178, 32.433 KB/sec Queued mail for delivery
-> QUIT

I've filed a report to Microsoft hoping they're of help.

michaelmurfy

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#2022173 25-May-2018 01:09

Update: Emails are now magically getting delivered to Microsoft related emails but are getting marked as Spam despite SPF / DKIM / DMARC passing. They're the only provider out of a list of 135 I tested that is marking the emails as spam, all the rest get through.

Glad to know it was a Microsoft problem. Thanks to those who helped me investigate over DM also.