Microsoft Silently Dropping Emails – a Sad but True Story

From time to time Microsoft decides to block or even silently drop emails that are sent by my selfhosted email server. It’s always a pain and takes a lot of effort to deal with it. This time I decided to document the whole process and how I dealt with it.

Thursday, September 24th, 2020

A customer of mine informed me that he got a strange email and asked me what is was. It was saying:

This is the mail system at host ***.******.***.

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

<*********@hotmail.de>: host eur.olc.protection.outlook.com[104.47.18.97]
said: 550 5.7.1 Unfortunately, messages from [***.***.***.***] weren't sent.
Please contact your Internet service provider since part of their network
is on our block list (S3150). You can also refer your provider to
http://mail.live.com/mail/troubleshooting.aspx#errors.
[AM6EUR05FT010.eop-eur05.prod.protection.outlook.com] (in reply to MAIL
FROM command)

*Sigh* Here we go again… I already now this. It happened to me many times. And I am sure it happened to many admins around the globe that are hosting an own email environment.

First aid to restore reliable delivery

But this time I am prepared to avoid a long outage time of email services for my customers and just turn on my email relay solution I described in this article: https://www.nerd-quickies.net/2020/07/10/solve-microsoft-email-block-list-errors-instantly/ I prepared this workaround especially for Microsoft related email delivery problems as this is the only company giving me trouble in this regard.

Open a ticket with Microsoft

After doing this I can take my time to fill out the Microsoft support form. It isn’t easy to find, so here is the link: https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75

I filled out the form, submitted it and prepared to wait. There just isn’t more you can do. The answer can take hours or days. You just don’t know. Therefore it is important to have a workaround in place (like setting up a relay as mentioned before).

Saturday, September 26th, 2020

Microsoft answered to my ticket:

Dear ***** *******

Please note that your ticket number is in the subject line of this mail.
***.***.***.***/32

Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.

Thank you,

Outlook.com Deliverability Support

Please do not reply to this message as it is from an unattended mailbox. Any replies to this email will not be responded to or forwarded. This service is used for outgoing emails only and cannot respond to inquiries.

Well. I already know this email from my previous cases but it puts a smile to my face whenever I get it again. “Errors are unlikely”? Really? I spent a lot of time filling out a form describing the “unlinkely error” I got and all the details.

Fortunately I got another email from Microsoft the same day that sounds a lot better:

Dear ***** ******

We have completed reviewing the IP(s) you submitted. The following table contains the results of our investigation.

Conditionally mitigated
***.***.***.***/32
Our investigation has determined that the above IP(s) qualify for conditional mitigation. These IP(s) have been unblocked, but may be subject to low daily email limits until they have established a good reputation.

Please note that mitigating this issue does not guarantee that your email will be delivered to a user’s inbox.

Ongoing complaints from users will result in removal of the mitigation.
Mitigation may take 24 – 48 hours to replicate completely throughout our system.

If you feel your issue is not yet resolved, please reply to this email and one of our support team members will contact you for further investigation.

Regardless of the deliverability status, Outlook.com recommends that all senders join two free programs that provide visibility into the Outlook.com traffic on your sending IP(s), the sending IP reputation with Outlook.com and the Outlook.com user complaint rates.

Junk Email Reporting program (JMRP) When an Outlook.com user marks an email as “junk”, senders enrolled in this program get a copy of the mail forwarded to the email address of their choice. It allows senders to see which mails are being marked as junk and to identify mail traffic you did not intend to send. To join, please visit http://support.msn.com/eform.aspx?productKey=edfsjmrpp&page=support_home_options_form_byemail&ct=eformts.

Smart Network Data Services program (SNDS). This program allows you to monitor the ‘health’ and reputation of your registered IPs by providing data about traffic such as mail volume and complaint rates seen originating from your IPs. To register, please visit http://postmaster.live.com/snds/.

There is no silver bullet to maintaining or improving good IP reputation, but these programs help you proactively manage your email eco-system to help better ensure deliverability to Outlook.com users.

Thank you,

Outlook.com Deliverability Support

That sound promising. As I have my working relay workaround in place I decide to wait the “24 – 48 hours” to give Microsoft the time to “replicate mitigation completely throughout their system”.

Wednsday, September 30th, 2020

Today is the day! Time to check if email delivery is working again.

I turned off my relay workaround and sent an email from one of my domains to one of my outlook email addresses to test email delivery.

Good news: I don’t get error messages anymore, no bounce errors, nothing. Very good.

Bad news: my email isn’t delivered. It isn’t in my Outlook inbox, not in my spam folder. It just disappeared.

Maybe it is a problem on my side? I checked my email server log. It is saying:

Sep 30 14:46:55 name_of_my_server postfix/smtp[14421]: E60F6276921: to=<********@outlook.de>, relay=eur.olc.protection.outlook.com[104.47.10.33]:25, delay=2.8, delays=0.01/0.04/0.78/2, dsn=2.6.0, status=sent (250 2.6.0 <691a0697-6a0c-99e8-89d1-5f59bd4d7968@******.***> [InternalId=60133837151113, Hostname=DB5EUR03HT193.eop-EUR03.prod.protection.outlook.com] 9424 bytes in 0.087, 105.555 KB/sec Queued mail for delivery -> 250 2.1.5)

“Queued mail for delivery” sounds good. Unfortunately the email was never delivered.

So, Microsoft’s “mitigation” made a bad problem (block of legitimate emails with an error message) even worse (drop legitimate emails without notice).

In fact, in my eyes this is the worst case: Accepting an email for delivery, then just delete it without telling anyone. I still wonder why a big company like Microsoft behaves this way and gets their own customers in such serious trouble.

But it is not the first time this happens to me. So I know what I have to do.

First: turn back on my Microsoft email relay workaround to restore reliable email service for my customers.

Second: Beg Microsoft to throw me a bone.

So I answered to their last email:

Commendably, I received an answer in less than two hours:

Hello,

My name is ******** ****** and I work with the Outlook.com Sender Support Team.

I do not see anything offhand with the IP: (***.***.***.***/32) that would be preventing your mail from reaching our customers.

You may be able to find additional information on common delivery questions at the Outlook.com Postmaster Site found at http://postmaster.msn.com/ I would like to highlight some key areas that I believe are appropriate to your company.

· Outlook.com has created the Smart Network Data Services (SNDS) program. This is a service that helps legitimate email senders work with their customers and partners to reduce spam originating from their IP. To register, please go to http://postmaster.msn.com/snds/ This program allows a sender to monitor the ‘health’ of their IPs.

· Monitor user complaints. Outlook.com also has a sender complaint feedback loop program called the Junk Email Reporting Program (JMRP). Enrollment in this free program will benefit you as a sender as it will keep your email lists updated and populated with interested Outlook.com customers. This program will help you to remove those Outlook.com customers who do not want to receive emails from your company. If you are interested in joining this program, please visit https://postmaster.live.com/snds/JMRP.aspx?wa=wsignin1.0.

While using the SNDS tool and enrollment in the JMRP will not allow emails from your mail servers to bypass our filters, these are in place to help legitimate companies deliver their emails to Outlook.com customers.

Apply for the Sender Score Certified Mail program.
If you are doing all the above and you continue to have deliverability issues, you may wish to consider joining the Sender Score Certified Mail Program, a third party program administered by Return Path, Inc. Many legitimate mailers and marketers have qualified and joined this program to improve mail deliverability and decrease email from being filtered to the Junk E-mail Folder. Sender Score (www.senderscorecertified.com) is the only service to which we subscribe

The troubleshooting steps in this email are recommendations only. Microsoft makes no guarantees that following these steps will guarantee deliverability to MSN, Outlook.com, or Live.com customers.

For more detailed information about best sending practices to Outlook.com users, please review the following white paper: http://download.microsoft.com/download/e/3/3/e3397e7c-17a6-497d-9693-78f80be272fb/enhance_deliver.pdf

Sincerely,
******* ********
Outlook.com Deliverability Support

*Sigh* I know this canned email already. Whenever I have delivery problems with Microsoft they send it to me at some stage. First time when I received it I spent many hours in studying all the links, documents, best practices. I registered for their SNDS and JMRP programs.

Therefore I can say that I follow all their rules as good as I can. There must be a very specific problem that they identified on their side. It can’t be a general problem because only Microsoft complains about it.

I decided that this was enough frustration for one day and to answer it the next day.

Thursday, October 1st, 2020

What a nice day! Time to spend some more time with Microsoft related email delivery problems…

I answered the following to their last email:

About 2 hours later I got this answer from Microsoft:

Thank you, Microsoft. That was really helpful. Instead of just looking at the specific case I get the same general information over and over again.

So i answered this:

Monday, October 19th, 2020

Didn’t hear anything from Microsoft for 18 days. Maybe the problem was solved and emails from my customers are getting to Microsoft customers’ inboxes now?

I turned off my relay workaround and again sent an email from one of my domains to an Outlook email address. Microsoft servers still accept my emails for delivery:

Oct 19 13:50:40 name_of_my_server postfix/smtp[2976]: 3535826181E: to=********@outlook.de, relay=eur.olc.protection.outlook.com[104.47.18.161]:25, delay=0.62, delays=0.1/0.07/0.13/0.33, dsn=2.6.0, status=sent (250 2.6.0 e68c995a-aa92-8ff0-b364-a2f79ff54d2a@******.*** [InternalId=22728967015364, Hostname=AM7EUR06HT223.eop-eur06.prod.protection.outlook.com] 9784 bytes in 0.178, 53.526 KB/sec Queued mail for delivery -> 250 2.1.5)

But you already guessed it: All emails are still dropped without any notice to sender, recipient or email server operator.

As my relay workaround shouldn’t be a permanent solution I decided to kindly ask Microsoft what the current status is. So I answered to their last email:

The answer took only a few minutes:

Thank you for contacting Microsoft Technical Support. The service request has been archived due to inactivity. If you still require assistance, please contact us via support.microsoft.com or 1-800-Microsoft.

REALLY? They closed my ticket without a warning? After everything we’ve been trough? “Due to inactivity”? Inactivity? Yes, they were inactive and didn’t solve the problem… No option to reopen the case? No help but the link on just the general support page?

To be honest: it took me some time to calm down.

As bad is it is. This problem is still open and has to be solved. So: Everything back to start!

First: Visit https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75 again, fill out the form an provide all details they need.

I’m quite used to it so it took me only 15 minutes or so.

Solved the captcha and hit “Submit”. This is what happened:

Noooooo. What is this? Microsoft? What are you doing to me?

Because I thought this could be one of those general error messages that could be caused by anything I spent about 2 hours using different browsers, cookie and blocking configurations. I even tried to adjust the content of the form fields. In the end I gave up. Maybe it really is a temporary problem on Microsoft’s side.

Tuesday, October 20th, 2020

New day, new luck.

Spent a little more time to get my “new” support case opened. But I get the exact same nonspecific error message.

What next? Wait a bit longer till the support page is fixed? Open a thread in the support forum?

All I want is to get a few legit, normal emails into the inboxes of Microsoft customers. Do I really have to spend half my life to achieve this?

Update

Seems, the support page is working again. I just submitted a new support request.

In the “Copy and paste any error messages:” sections I wrote the following:

There is no error message. Emails are just dropped without notice and don’t reach inboxes of your customers!

Sending from sample@mydomain.tld to *********@outlook.de results in this line in my log. Your server says “Queued mail for delivery” but it does not reach the inbox or even spam folder on your side. It just disappears somewhere in your infrastructure.

Oct 19 13:50:40 name_of_my_server postfix/smtp[2976]: 3535826181E: to=<********@outlook.de>, relay=eur.olc.protection.outlook.com[104.47.18.161]:25, delay=0.62, delays=0.1/0.07/0.13/0.33, dsn=2.6.0, status=sent (
250 2.6.0 <e68c995a-aa92-8ff0-b364-a2f79ff54d2a@*******.***> [InternalId=22728967015364, Hostname=AM7EUR06HT223.eop-eur06.prod.protection.outlook.com] 9784 bytes in 0.178, 53.526 KB/sec Queued mail for delivery -> 250 2.1.5)

The problem exists for over 3 weeks now. Last ticket SRX1509453967ID was closed by you without solving the problem.

Thursday, October 22nd, 2020

Got an email from Micrsoft support today:

Dear ****** *******

Please note that your ticket number is in the subject line of this mail.
***.***.***.***

Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.

Thank you,

Outlook.com Deliverability Support

Please do not reply to this message as it is from an unattended mailbox. Any replies to this email will not be responded to or forwarded. This service is used for outgoing emails only and cannot respond to inquiries.

Sounds familiar, doesn’t it? The fact that you reported a real error seems to be irrelevant if Microsoft thinks it is unlikely.

But as I am not supposed to answer I just waited a little longer and received this email 29 minutes later:

Dear ***** ******

We have completed reviewing the IP(s) you submitted. The following table contains the results of our investigation.

Not qualified for mitigation
***.***.***.***
Our investigation has determined that the above IP(s) do not qualify for mitigation.

Please ensure your emails comply with the Outlook.com policies, practices and guidelines found here: http://mail.live.com/mail/policies.aspx.

To have Deliverability Support investigate further, please reply to this email with a detailed description of the problem you are having, including specific error messages, and an agent will contact you.

Regardless of the deliverability status, Outlook.com recommends that all senders join two free programs that provide visibility into the Outlook.com traffic on your sending IP(s), the sending IP reputation with Outlook.com and the Outlook.com user complaint rates.

Junk Email Reporting program (JMRP) When an Outlook.com user marks an email as “junk”, senders enrolled in this program get a copy of the mail forwarded to the email address of their choice. It allows senders to see which mails are being marked as junk and to identify mail traffic you did not intend to send. To join, please visit http://support.msn.com/eform.aspx?productKey=edfsjmrpp&page=support_home_options_form_byemail&ct=eformts.

Smart Network Data Services program (SNDS). This program allows you to monitor the ‘health’ and reputation of your registered IPs by providing data about traffic such as mail volume and complaint rates seen originating from your IPs. To register, please visit http://postmaster.live.com/snds/.

There is no silver bullet to maintaining or improving good IP reputation, but these programs help you proactively manage your email eco-system to help better ensure deliverability to Outlook.com users.

Thank you,

Outlook.com Deliverability Support

This time I am “not qualified for mitigation”. Unfortunately I don’t know why. Instead, just all the general information that I already know inside out and that I am already following as good as I can.

Even if I begin to loose hope, I answered the following:

Answer comes very quick after about 1 hour:

Hello,

My name is ******** and I work with the Outlook.com Sender Support Team.

I do not see anything offhand with the IP: (***.***.***.***) that would be preventing your mail from reaching our customers.

You may be able to find additional information on common delivery questions at the Outlook.com Postmaster Site found at http://postmaster.msn.com/ I would like to highlight some key areas that I believe are appropriate to your company.

· Outlook.com has created the Smart Network Data Services (SNDS) program. This is a service that helps legitimate email senders work with their customers and partners to reduce spam originating from their IP. To register, please go to http://postmaster.msn.com/snds/ This program allows a sender to monitor the ‘health’ of their IPs.

· Monitor user complaints. Outlook.com also has a sender complaint feedback loop program called the Junk Email Reporting Program (JMRP). Enrollment in this free program will benefit you as a sender as it will keep your email lists updated and populated with interested Outlook.com customers. This program will help you to remove those Outlook.com customers who do not want to receive emails from your company. If you are interested in joining this program, please visit https://postmaster.live.com/snds/JMRP.aspx?wa=wsignin1.0.

While using the SNDS tool and enrollment in the JMRP will not allow emails from your mail servers to bypass our filters, these are in place to help legitimate companies deliver their emails to Outlook.com customers.

Apply for the Sender Score Certified Mail program.
If you are doing all the above and you continue to have deliverability issues, you may wish to consider joining the Sender Score Certified Mail Program, a third party program administered by Return Path, Inc. Many legitimate mailers and marketers have qualified and joined this program to improve mail deliverability and decrease email from being filtered to the Junk E-mail Folder. Sender Score (www.senderscorecertified.com) is the only service to which we subscribe

The troubleshooting steps in this email are recommendations only. Microsoft makes no guarantees that following these steps will guarantee deliverability to MSN, Outlook.com, or Live.com customers.

For more detailed information about best sending practices to Outlook.com users, please review the following white paper: http://download.microsoft.com/download/e/3/3/e3397e7c-17a6-497d-9693-78f80be272fb/enhance_deliver.pdf

Sincerely,
*******
Outlook.com Deliverability Support

Of course I was very disappointed because it was the exact same canned email I already know. Obviously nobody looked at the ticket I mentioned in my email. Apperently they didn’t read my email at all because they refer to all the “solutions” I already mentioned.

Unfortunately, I was busy with important things too. Fighting against windmills can’t be on my priority list anymore. Therefore I had to postpone my answer.

Wednesday, October 28th, 2020

Okay, time to deal with my personal never ending story again. The last thing I want is Microsoft closing the ticket “due to inactivity” again.

I just turned off my relay workaround and tried to send an email from one of my domains to my Outlook email address – just to be sure the problem persists. Of course it does.

So I turned the relay on again and wrote another email to Microsoft. Because there just is no new information on my side I sent kind of canned email too:

After 2 hours I got a pretty promising answer:

Hello,

My name is ******* and I work with the Outlook.com Deliverability Support Team.

We will be looking into this issue along with the Escalations Team. We understand the urgency of this issue and will provide an update as soon as this is available. Rest assured that this ticket is being tracked and we will get back to you as soon as we have more information to offer.

Thank you for your patience.

Sincerely,
********
Outlook.com Deliverability Support

Thursday, October 29th, 2020

Got an email from Microsoft today:

Okay. Seems like SmartScreen was blocking my emails for some reason. But my IP is is eligible for another temporary mitigation. Sounds promising! Because I don’t have the time to test it right away and it could take up to 48 hours to “replicate completely throughout Microsoft’s systems” I decide to do the test on Monday. Luckily I still have my working workaround in place. So there is no need to rush.

Monday, November 2nd, 2020

The problem was solved! Emails are being delivered again 🙂

Conclusion

Although I am very glad about the happy ending of a long story, this is not very satisfiying because I never figured out what the problem was. My emails were deleted by a proprietary “SmartScreen” without notice. Couldn’t learn a lesson this way. This was the 3rd time this exact same problem occured on the same server. And it will likely happen again because I have no idea what to improve.

Like many adminstrators I do my best to implement all recommendations as far as possible. I have SPF, DKIM, DMARC records and spam filters in place. I am member of JMRP and SNDS program (never got a complaint). As far as I know, emails from my business custmers are branded, formatted following best practices, have unsubscribe links and a valid contact footer.

I host many email domains on this server. Most are used by private persons, some are business related. Of course private users will not brand their emails, format them using best practices, add opt-out links or a contact footer. So unfortunately for an adminstrator options are limited.

Biggest problem is, that Microsoft always blacklists the whole server! If only one of my customers does something not in line with the secret rules of SmartScreen, emails of all other customers are blocked too. IMHO this is just unprofessional. Why not just block the domain under suspicion and send the adminstrator a message (maybe as part of the JMRP)?

For me the only way to deal with this topic is to sit and wait until it happens again.

Next time I can only do the same thing that I documented in this blog article: activate my relay workaround, open a ticket via https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75 and push it forward until it is solved.

---

Was this article helpful?

Consider buying me a coffee to keep my brain fueled 🙂