How to Optimize Email Deliverability for Your Users

How’s your email deliverability for subscribers who use Microsoft’s as their Internet service provider (ISP)? Here we focus on deliverability issues specific to based on some of the latest information revealed at the 2015 Email Evolution Conference (EEC).

The final session at this year’s EEC featured four representatives of the largest ISPs – including John Scarrow from Microsoft – who answered questions from email marketers on deliverability.

Microsoft Personalizes Deliverability

According to Scarrow, deliverability has become more personalized for Microsoft. subscribers today control whether or not an email is delivered to their inbox. For example, specific actions taken in the past by a user – such as opening or deleting certain messages – help determine how other messages from a sender get delivered to that individual’s inbox.

In fact, much of Microsoft’s sender reputation scoring is based on machine learning algorithms, which are heavily driven by user input. Microsoft also leverages some external blacklists as part of building reputation scores; however, Scarrow didn’t indicate which blacklists uses.

For, a bad sender reputation is usually a result of noncompliance with Microsoft’s policies and guidelines. And if senders have done something wrong, Microsoft will hold them accountable. On the other hand, if a server had a breach and senders can legitimately explain it, Microsoft will work with the senders to get their reputation score corrected.

Does your organization currently share transactional email and internal company email? That practice is okay with Microsoft, said Scarrow. You may have issues with deliverability, however, if you then use the same IP to send marketing mail. Some companies try to add transactional email to promotional email in an attempt to get a lift in reputation. That practice is not recommended. Transactional emails should always be sent separately from promotional emails.

Engagement Indicators for

As detailed in a recent feature on deliverability, Microsoft and other ISPs look at whether an email is opened, but not if it’s clicked. Microsoft doesn’t use clicks as a measure of engagement due to user privacy considerations. This was a surprising revelation, as most email marketers previously believed that ISPs used clicks as an important measure of subscriber engagement.

Scarrow described what does drive engagement – and hence better sender reputation – in the eyes of Microsoft:

  • Deleting an email without opening it is bad for a sender’s reputation. This is an indication that that a user determines an email’s content is irrelevant just by the sender address.
  • Moving an email from one folder to another is good for a sender’s reputation because it indicates the user is interested in the email content.
  • Moving an email out of the junk folder is exceptionally good for a sender’s reputation, as it’s a strong indicator of the user’s interest.

As far as email account closure and spam trap policies are concerned, Scarrow indicated that after 2 years of not being used, an account goes inactive. Microsoft doesn’t use inactive addresses as spam traps.

Should You Mail to Inactive Subscribers?

For Microsoft, inactive subscribers don’t directly affect sender reputation, unless those subscribers decide to mark your emails as spam. Keep in mind, however, that deleting an email without opening it is a negative signal for ISPs (including, so your emails sent to inactive subscribers may still end up in the junk folder.

In terms of increasing engagement and especially email opens, Scarrow believes that marketers really need to work on subject lines to strike a balance between saying too much versus saying too little. If you say too much, your email may not get opened. But if you say too little, people won’t open it.

Some other pieces of advice from Scarrow:

Check out the following links for additional information about’s deliverability guidelines, policies, and troubleshooting advice:

  • Postmaster This is an informational site designed for IT professionals who send email to
  • Policies, Practices, and Guidelines This link provides guidance to help senders avoid deliverability issues by outlining the industry’s best practices and regulations in place at Microsoft to protect users from getting unwanted emails.
  • Troubleshooting If you’ve already checked out the Policies and Guidelines page and you’re still having trouble delivering email to recipients, this link discusses solutions to common problems.

If your company is looking for ways to optimize your email deliverability, FulcrumTech can help. Email us or give us a call at 215-489-9336 and get started today.


Other Articles You Might Like

Sign Up for NewsLever

Our free, monthly email newsletter

NewsLever is our free, monthly e-newsletter for B2B and B2C professionals who want to develop and implement powerful email-marketing campaigns that build relationships with prospects and customers.

  • This field is for validation purposes and should be left unchanged.

Privacy Policy|Learn More|Current Issue