How to Check Microsoft's Blacklist


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Are you suspicious that you are on Microsoft Exchange’s blacklist is blocking your emails?  If you’re looking for a site to check if your IP address are on Microsoft’s blacklist – look no further:  Microsoft Exchange’s blacklist is privately maintained so you can’t query it directly.  However, we’ll show you how to check if you are on Microsoft’s blacklist and if you are,  how to request removal from the Microsoft blacklist.

This article only applies to email blocked by Microsoft’s Hosted Exchange.  You’ll need to check this article to learn more about blacklist issues with Microsoft or Microsoft email services.

As with all of our articles on email blacklist management – we assume you are being a responsible email netizen and not sending spam.  And we also assume you’re probably an Email administrator or IT dude (or ‘dudette’?).  If you’re an individual and you’re having email delivery issues, you’ll probably need the help of your IT team to get access to some of the information here or better yet – send them to this link directly.

Microsoft Exchange Blacklist – Background

Because Microsoft’s Hosted Exchange blacklist is private – neither you nor a blacklist monitoring service can pro-actively monitor it to see if your emails are being blocked. The only way to find out if you’re blocked is by checking your email server log files (see next section), or waiting until your users or recipients complain.

Microsoft Hosted Exchange and ‘’.  You also need to know that ‘’ is the email server domain used by Microsoft for their Forefront Online Protection for Exchange (FOPE). For example, Office365 — Microsoft’s subscription-based version of Office, includes hosted Exchange.

In fact, if you go to – you’ll end up on Microsoft’s Hosted Exchange Server product page (‘Microsoft Exchange Online’.)

How To Check if You’re On Microsoft’s Hosted Exchange Blacklist

Microsoft’s email filter is privately maintained, so you’ll likely discover that your emails are being blocked by Microsoft in 1 of 3 ways:

  • A recipient actually reports to you that they are not receiving your email (i.e., upset user / customer)
  • If your email is being blocked by recipients using Microsoft Hosted Exchange, your IT team will see a log entry in your email server logs that looks like this (xx.xx.xx.xx will be your email server’s IP address):

failed,5.7.1 smtp;550 5.7.1 Service unavailable; Client host [xx.xx.xx.xx] blocked using Blocklist 1, mail from IP banned; To request removal from this list please forward this message to and include your ip address xx.xx.xx.xx.

  • When you send an email and are being blocked, you’ll receive an ‘NDR’ – Non-Delivery-Report’ email similar to the following.  Be sure to save it for your trusty IT folks, cuz they’ll need this to resolve the issue:

Reporting-MTA: dns;
Final-Recipient: rfc822;

Action: failed
Status: 5.5.0
Diagnostic-Code: smtp;550 Service unavailable; Client host [xx.xx.xx.xx] blocked using  Blocklist 1, mail from IP banned by; To request removal from this list please forward this message to delist -at- and include your ip address xx.xx.xx.xx”

NOTE: If you’re having issues with Microsoft’s hosted Exchange and are seeing errors from ’88.blocklist.zap’ in your email log files or NDR reports,  check our related article about 88.blocklist.zap (which is an earlier version of the blacklist that is still in use by some companies.)

How to Get Removed from Microsoft Exchange Blacklist

As a reputable email service provider for businesses, we have to start with the obvious: be sure you’re not spamming before you make your request.  If you or your company are sending unsolicited emails or general spam – you’ll need to clean up your internal practices before taking the steps below, or Microsoft will promptly deny your request, or they’ll process it and you’ll find yourself being blocked again right away.  That said, you can request removal you will need the following information:

  • Grab the log entry with the specific error message or the (NDR email if you received one) from your email server.
  • You’ll need the IP address of your email server (the sending IP address).  You’ll probably need your IT team’s assistance to get this info.
  • You’ll also need the email address you sent the email to and the send-from.
  • Ideally,  include a copy of the email.

Once  you may request delisting by sending an email to delist -at- (replace the -at- with ‘@’ to make it a real address) with the above information, including the IP address you want removed from their list.

If you’re a Microsoft Hosted Exchange customer, you can also try sending the above info to: false_positive -at-

Another option to consider

If your marketing team is sending permission-based email campaigns and/or wants to automate your emails with autoresponders or trigger campaigns, consider using an email service provider like Pinpointe.  We deal with all this blacklist stuff 24×7 so you don’t have to.  We maintain one of the highest inbox delivery rates for customers.  We monitor email delivery on an ongoing, real-time basis and ensure that you’re opt-in emails won’t get blocked.  You can sign up for a free trial any time.  Request a free trial or schedule a demo.



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