Unable to deliver to some domains managed by Office365


I recently set up MiaB, with a domain from Namecheap and an instance from BuyVM (in Europe, if that makes any difference). I’m having trouble delivering to Office365 domains, particularly academic domains.

To provide some examples:

  • Mail to outlook.com is delivered to Junk. After marking these as not spam, they deliver.
  • Mail to yale.edu (Yale/NHH) is delivered to Junk. After marking these as not spam, they deliver.

But, and more importantly:

  • Mail to stanford.edu doesn’t even appear in Junk.
  • Mail to uchicago.edu doesn’t even appear in Junk.

I’ve signed up for JMRP and SNDS, and filled out a report at https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75 for uchicago.edu and received a reply that they found no errors.

Anyone seen an issue like this? If anyone has a moment it could be helpful if you could try emailing me from a MiaB to moerner@uchicago.edu, and I could see if I can get your email. Could be something idiosyncratic about their setup (and Stanford’s).


Sent …

Thank you @alento, and for others: I got that message. So something is wrong with my setup at moerner.com. That’s good to know.

Ok, on to troubleshooting. @dmoerner

Send an email to the email address provided by mail-tester.com and let me know the results link (PM is ok if you prefer).

Thank you for your help. Here is a results link:


Unfortunately nothing seems to stand out. One other thing I tried before doing this is to switch to sending HTML email; previously I was sending text email. Unfortunately, HTML email still didn’t go through to the problematic domains.

Can’t get any more perfect than that. So let’s look into the mail logs on your VPS … got the time and energy?

Yes, I do! I’m happy to dig, but it would be helpful if you should point me to where I should look.

Start with checking the mail queue.


The response should be:

# mailq
Mail queue is empty

Just a note @dmoerner … when this thread hits 20 messages you will not be able to respond any more today. Perhaps we should move this to Slack?


Thanks, @alento: First, the mailq is empty. Second, I’m happy to move to Slack, although I’m about to be in 5 hours of meetings, so I don’t think I’ll hit the 20 message limit today!

Ok so … how are you at reading log files? :stuck_out_tongue:

Open a second SSH window (optional) and run this

tail -f /var/log/mail.log

Then send an email to the uchicago address and capture the log entries. They may give a clue …

The logs seem OK:

Jul 30 13:47:15 box postfix/smtp[25210]: 3F0631A8: to=<moerner@uchicago.edu>, relay=mxb-002fc702.gslb.pphosted.com[]:25, delay=3.2, delays=0.12/0.04/2/1, dsn=2.0.0, status=sent (250 2.0.0 32gee17t35-1 Message accepted for delivery)

I think I figured out the problem: I’m getting blocked by Proofpoint. They don’t list my IP address as blocked (https://ipcheck.proofpoint.com/?ip=, and nothing shows up in my logs in my Proofpoint quarantine panel, but when I explicitly whitelist my MiaB address, the email goes through. I also don’t see Proofpoint errors in /var/log/mail.log, only things like this:

Jul 30 13:48:21 box postfix/smtp[25210]: mxb-002fc702.gslb.pphosted.com[]:25: depth=0 verify=1 subject=/C=US/ST=California/L=Sunnyvale/O=Proofpoint, Inc./OU=ESP/CN=*.pphosted.com

It seems like there are a number of threads about Proofpoint, so I’ll look through those and try to figure out how to contact them, hopefully through my employer who uses them.


Oh wait, you already knew that.

Yeah your IT department’s next step is to contact ProofPoint.

Good luck!