A Marketer’s Field Guide to Microsoft Hotmail Email Inboxes

Microsoft is the largest email provider in the world hosting over a billion mailboxes with 350 million active users. More than 8 billion emails are handled each day with 30-35% of those emails making it to the inbox. Microsoft’s brands and domains include Windows Live Hotmail (hotmail.com), MSN (msn.com) and Windows Live (live.com). The most popular domain of the three is by far Hotmail.

HoTMaiL was one of the first web-based email services and was launched in 1996. Its popularity now spans the world. Hotmail is not only one of the most popular domains in the United States but also dominates markets in Brazil, Australia and most European countries. Microsoft has established offices throughout the world to support its email infrastructure providing them with the insight needed to tailor their tools and services to a diverse set of global users.

The one thing we at Return Path love about Microsoft is the ecosystem they have built to protect both users and senders against spam. Smart Network Data Services (SNDS) was created a few years ago to provide senders with a free tool to monitor traffic coming from their IP addresses into Microsoft’s email servers. This data includes statistics on email volume, complaints, spam traps and other useful information about your email program.

User base profile. We picked up some great demographics on Hotmail users from hunch.com. According to their study, the majority of Hotmail users are 18-34 (and younger) and have a high school diploma. They are 48% likely to be single, typically live in the suburbs, own a laptop and wear t-shirts and jeans. They are 13% more likely to be introverts than extroverts but are well-traveled with 68% having visited five or more countries. If you want to attempt some list targeting by ISP then you should read the rest of the Hunch article.

Spam filtering. Hotmail utilizes Microsoft's patented SmartScreen anti-spam filtering technology. This technology uses a machine-learning approach to help protect users' inboxes from junk e-mail. SmartScreen technology learns from known spam and phishing threats as well as from Hotmail customers who have chosen to participate in the Feedback Loop Program (FBL).

Like many ISPs, Microsoft considers volume, spam complaints and spam traps into their filtering. However, the company places a significant proportion of their filtering decisions from data in their Sender Reputation Data (SRD) network. Along with other sources of reputation data such as the Junk e-Mail Reporting Program (JMRP), the SRD helps to train and improve the way SmartScreen technology classifies messages based on email content and sender reputation. Participants in the SRD program are selected from active Hotmail users at random from over 200 countries and no one is allowed to volunteer for the program. Their votes on whether or not they think your email looks spammy holds a lot of weight in filtering.

Sending reputation. SNDS is a tool that not only can provide you with detailed data about your sender reputation and deliverability at Hotmail but it can also be an indicator of what may be happening at other ISPs. Microsoft is now watching volume spikes so be consistent with your mail programs over time. Keep an eye on the color codes within SNDS – if you are seeing green, you should see strong statistics across the board. If you are seeing yellow, it’s a coin toss as to how your email will be handled. If you are seeing red, it’s time to go back to the drawing board with your email program!

Feedback loops. Microsoft offers Junk e-Mail Reporting Program (JMRP) as a free service to anyone who wants to sign up. These FBLs are the result of spam complaints originating from Hotmail users – not SRD participants. You should remove these complainers from your list immediately to improve your sending reputation with Microsoft and keep your email lists clean. You should also review the email headers to see if it was marked as “junk” or “phishing” so you can make the proper adjustments to your email program, content or practices.

Prioritized delivery. Microsoft does not maintain a proprietary whitelist. They do however participate in Return Path’s Email Certified Whitelist Program. Participants in this program will bypass all spam filters and have their email delivered to Hotmail users with images on.

Sending infrastructure requirements. Microsoft, along with some other industry leaders, invented the Sender ID Framework to help counter email spoofing used by spammers. Sender ID is implemented using Sender of Policy Framework (SPF) authentication records and should be implemented in all email sent to Microsoft. Last year Microsoft starting conducting DomainKeys Identified Mail (DKIM) checks on inbound email. DKIM will be checked if Sender ID fails. If both authentication methods fail then their filters will make a decision to bulk the email or drop it all together.

Partners. Microsoft has only one known partner that uses its infrastructure and that is Sympatico (Bell Canada).

That’s it for Microsoft. Stay tuned for the next blog in my Email Marketer’s Field Guide series! Don't forget to check out the last entry in the Field Guide series - Yahoo! Inboxes