Microsoft Domains Block List – May 2020 (Resolved)


UPDATE: May 28 @ 9:00am Microsoft has removed the block, please allow 24 hours

We would like to thank everyone for their patience during this interruption. We apologize about the time it took for it to be resolved. A 2 week interruption is an unacceptable amount of time, and nearly all of that was spend waiting for Microsoft to address our issue. I have passed on my concerns on behalf of everyone on Server 2 (, and sincerely hope that their support moves quicker if this happens again.

I have conducted an investigation into the emails originating from your IP space and have implemented mitigation for your deliverability problem. This process may take 24 – 48 hours to replicate completely throughout our system.

UPDATE: May 23 @ 12:00am we received an update to our ticket, Ayesha from the Microsoft Delivery Team will be investigating our issues:

My name is Ayesha and I work with the 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.


Ayesha Deliverability Support

UPDATE: May 20th @ 9:00am we have not received an update to the ticket number, nor have received any communications from Microsoft since being issued the ticket number.

UPDATE: May 15th @ 8:52pm we received a Ticket Number from Microsoft.

We are aware of issues with email deliverability from Server 2 ( to Microsoft domains starting around Monday May 11. Affected recipients have emails with:

  • Live
  • Hotmail
  • Outlook

Please be assured that we’re addressing this issue to the best of our ability, and that it is a very high priority for us to restore send-ability to Microsoft addresses. Please check this page for updates.

We have:

  • Audited sending activity to isolate the root cause:
    • Typically blocks are the result of individual Outlook, Live or Hotmail users reporting your emails as spam. We are subscribed to Microsoft’s portal SNDS (Smart Network Data Service) which should be reporting back to us which emails have been marked as spam. This has not happened; which leaves us little reasoning or policy changes we can address.
    • Outgoing mail volume is normal
    • Our SenderScore is maintaining at 99/100 (excellent)
  • Audited the sending IP ( in common email blocklist databases:

Support Requests:

  • May 12, 2020: Submitted ticket for support and manual audit for remediation to Outlook support
  • May 13, 2020: Submitted ticket for support and manual audit for remediation to Outlook support
  • May 14, 2020: Submitted ticket for support and manual audit for remediation to Outlook support
  • May 15, 2020: Submitted ticket for support and manual audit for remediation to Outlook support

Next Steps:

We will continue to request support from Microsoft to review their blocking policy for Server 2 ( This process is typically same-day, however Microsoft has been extremely slow in responding to our request; it’s likely the Covid-19 pandemic is affecting their staffing resources.

During this time you may want to communicate with any Live, Hotmail, or Outlook customers/clients via your personal email.


Domain-based email hosted alongside your website is often subjected to strict deliverability requirements. Because there is a huge volume of spam emails flying around the internet from web servers, the ‘free’ mail providers (outlook, live, hotmail, gmail, yahoo, etc) employ extraordinarily strong filters to lessen the amount of spam their users receive. This makes it difficult as a legitimate mailer to ensure your email is delivered to these free mail services.

Currently there are two solutions:

Solution 1:

Wait for Microsoft to review the support ticket and implement mitigation.

Solution 2:

Mail services are changing in the modern web. The big players – Microsoft and Google are pressuring self-hosted mail services like ours (by these exact circumstances) towards paid, dedicated mail services like:

By using one of the above services you will be subject to less stringent mail deliverability policies. For businesses where consistent deliverability is required, we strongly recommend upgrading to one of the above services for your email service. Eggplant does offer discounts on hosting packages for clients who are using a third-party mail service.

Written by Shawn Wernig

Shawn Wernig

Lead Creative at Eggplant Studios

Shawn Wernig is the lead creative behind Eggplant Studios. While not full time (let's face it, more than full time) designing websites for his clients, Shawn enjoys good beer, double-doubles, and hiding from his phone.