If you’ve read our articles about the Spamhaus and SURBL blocklists, you’re already aware that there are hundreds of email blocklists out there and they aren’t all created equal. Being listed by Spamhaus will absolutely devastate your deliverability across multiple mailbox providers. A SURBL listing can cause serious inboxing problems, but can also have impacts that extend beyond email deliverability. There are dozens of other listings that can cause real headaches for anyone sending email and hundreds of blocklists that are minor inconveniences at best. However, our position is that every time you end up on any blocklist, it’s a signal that your email program has room for improvement.
In this article, we’re going to discuss a blocklist that is somewhat unique in the email world, and that is Microsoft’s Blocklist.
Technically, all mailbox providers have a blocklist. What I mean by that, is that there is always some set of criteria that will cause a mailbox provider like Gmail, Yahoo, or Apple to start blocking your mail. Microsoft is no different. Like all mailbox providers, Microsoft uses dozens or hundreds of different signals to determine if your message will land in the inbox, the spam folder, or be blocked outright. What is unique about Microsoft is that they are the only major mailbox provider that operates a blocklist that senders can actually query and monitor.
The Microsoft blocklist is different from other blocklists in some very important ways. Most blocklists can be queried over DNS. That’s why they are often called DNSBLs. Microsoft doesn’t operate a DNSBL. Their blocklist can only be viewed from inside their Smart Network Data Service (SNDS) portal. With SNDS, senders can monitor a number of reputation signals from Microsoft that tell you a great deal about what their filters think of your email traffic. SNDS is where you’ll also see if any of your IP addresses are being blocked. It is also where you can request a delisting.
How To Check Your Status
In order to check your status, you have to sign up for Microsoft’s SNDS service. Signing up is easy, but there is an additional step you need to take in order to see anything interesting about your reputation. After signing up, you need to request access to view data about your sending IPs. This involves proving you own the IP address(es) that you use to send your email. Most senders rely on an Email Service Provider (ESP) to send their email. In most cases, your sending IP is owned by your ESP. In most cases, your ESP has to grant you permission to see your SNDS reputation data. This process is slightly different with each ESP, but generally starts with a support ticket.
Once you’ve signed up and proven ownership or permission to view reputation data, you’ll see a tab in the SNDS portal that says IP Status. If this page looks like this, you’re in good shape!
If the page shows something like this, it means you’re on their blocklist:
The example above shows a typical listing that was caused by excessive complaints, low engagement, or spam trap hits. However, the “Details” section will sometimes reference other reasons for the listing including third-party blocklists like Spamhaus. If your IP Status page references a third party blocklist, you’ll need to contact them instead of Microsoft in order to get unblocked.
How Do You Get On The List?
There isn’t one specific cause for a listing like this. It is almost always a combination of things. Microsoft’s spam filters are analyzing hundreds of signals to determine how they are going to treat your email. These signals include, but are not limited to:
- Recipient engagement
- List hygiene
- Bounce rate
- Spam Complaint rate
- Spam trap hits
- SRD Votes
If any combination of these metrics get out of line, your email will start landing in the spam folder. If they get extremely out of line, your IP address(es) can end up on their blocklist. Keeping these metrics in check requires consistent monitoring and maintenance of your email program. The days of “set it and forget it” are long gone. Spam filters and blocklists reward those who pay attention to the details of their email efforts.
What Happens When You’re Listed
If your IP has a Blocked status in SNDS, it means that 100% of your email going to Microsoft Outlook recipients will be rejected. It is possible to have some of your mail blocked without explicitly being on their list, but a Blocked status means you’re completely shut off from their mailboxes. The chart below shows the blocked email percentage for an actual sender who found themselves on the Microsoft blocklist. The consequences are devastating:
For a typical sender, Microsoft consumer mailboxes (Outlook.com, Hotmail.com, Live.com, msn.com) make up about 10-14% of your total email list. So ending up on the Microsoft block list can be extremely impactful to the ROI from your email efforts. When your IP address ends up on their list, you’ll immediately see a significant spike in non-delivered emails specifically to Microsoft mailboxes. If your email service provider allows you to see the actual rejection messages for non-delivered emails, the error message that is returned looks like this:
550 5.7.1 Unfortunately, messages from {your IP address} 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/
It is important to note that this blocklist only impacts messages that are sent to the Microsoft consumer mailboxes like Hotmail.com and others mentioned above. Microsoft also hosts business email addresses with their Microsoft 365 platform. These mailboxes run on different infrastructure and follow different filtering and blocking rules. Being on the Microsoft blocklist will not directly cause blocking at Microsoft 365 mailboxes.
Listed by Microsoft?
Talk to our team about getting delisted and keeping your IPs off the list.
Book a CallWhat To Do If You’re Listed
If you find yourself listed by Microsoft the best course of action is to immediately pause all outbound email going to Microsoft mailboxes. Continuing to send email while you're on the block list is a bad idea for two reasons; the messages won’t deliver, and you're sending Microsoft a signal that you aren’t paying attention to what they are telling you. Pausing your sending while you sort things out is the best first step.
The next thing you should do is sign up for Microsoft SNDS. The SNDS interface will give you some clues as to why you were listed. They will provide you with a Red/Yellow/Green status for your IP address(es) over time, daily sending volume, as well as your spam complaint rate. The interface looks like this:
It’s also a good idea to sign up for Microsoft’s spam complaint feedback loop called the Junk Mail Reporting Program (JMRP). If you use any of the mainstream ESPs like SendGrid, Mailgun, Mailchimp, Sparkpost, or countless others, the odds are that you’re already enrolled. One way to check is to review spam report data in your ESP’s console. If you see any spam reports that came from Microsoft domains, that means you are enrolled. If you’re sending with your own infrastructure, or you have never seen a spam complaint come in from a Microsoft mailbox, you probably are not enrolled. Senders can enroll in the JMRP through their Microsoft SNDS account.
Once you have a good idea of what their filters are saying about your sending, you can review their best practices recommendations and see if you’re falling short in any obvious ways. Once you’ve reviewed those and made some adjustments, the next step is to submit a delisting request. The form can be found here. We highly recommend going through the delisting process with one of our deliverability experts because the process can be pretty cryptic. You’ll receive vague responses from their frontline support team that are usually very unhelpful. They will rarely tell you specifically what you did to get listed and when they refuse to delist you, they don’t give you much information as to why they refused. This leaves a lot of senders very frustrated and confused about what to do next.
Easy, Reliable Delisting
SH Consulting has helped countless senders navigate the delisting process and put in place small, but impactful changes that will help prevent future listings. We work as a part of our client’s team to facilitate the entire process. It starts by understanding what your organization is doing with email, identifying areas where we can improve, and then submitting the delisting request. After the initial submission, we continue to work with your team on drafting clear and concise responses to Microsoft’s feedback about your listing status. Our goal is to effectively bridge the gap between your organization and the teams at Microsoft who are responsible for making listing/delisting decisions. Whether you’ve attempted to get delisted on your own and been rejected, or you’ve just found out that you’re listed and want to remediate the issue as quickly as possible, we provide an easy, reliable service to help you get back into your recipients’ mailboxes.
