Microsoft Deliverability Dilemmas Solved
Q. Why does my email get delivered to the junk folder in some people’s Outlook and delivered to the inbox in others?
A. Email that's sent to business addresses makes a difficult journey upstream, going through multiple spam filters before reaching its destination, often making inbox placement rate much more inconsistent. The most common paths are through gateway filters, hosted email providers, server OEM filters, desktop software, and email clients. Gateway filters are usually installed at the very border of the email network, and provide domain and IP based level of filtering. Server filters are installed on top of the mail server to filter out things like spam, viruses, and phishing messages. Like the gateway filters, server filters also use Bayesian content filtering, reputation filtering, and user feedback.
Hosted email is becoming an increasingly popular choice for businesses, and is offered by most email providers today like Google, Microsoft, and Yahoo. These systems use the same filtering as their webmail. Last, but not least, business emails go through an email server, which is usually Microsoft Exchange, and then through the email client, which in this case is Outlook.
The common thread with all Microsoft filtering products from Exchange to Outlook is their proprietary spam filter, Smart Screen. This filter looks at things like the URLs in the content, IP address, the number of complaints your IP address has generated, how long and consistently you’ve been mailing from your IP, and whether or not you authenticate. Outlook also learns from user input. Every time a subscriber marks a message as junk, it starts to filter other messages like it to junk, which could explain the differences you see in Outlook delivery. While it’s extremely difficult, if not downright impossible to make sure your email lands in the inbox at Outlook every time for every individual, there are some key things you can do to increase your chances for inbox placement.