Ryan from eROI attended a deliverability workshop a couple of days ago and says he learned a lot more  than he expected. Guest speaker at the event was Brian Holdsworth, product planner for Microsoft Hotmail. Here are a couple of highlights on what he talked about:

• Over 50% of email browser use is MS Outlook
• MS Outlook and Windows LiveMail (formerly Hotmail) represent 600 million people / users in the world. Microsoft expects this to climb to 1 billion in the next few years.
• Of the 4 billion emails per day that Hotmail processes, 90% is spam. Much of this is image spam, and spam generated from botnets and zombies.

Interestingly enough there seem to be some communication barriers within Microsoft. The Outlook team makes major changes/shifts every 3 years, and for Outlook 2007, they are moving to a content rendering engine built in MS Word instead of the natural choice of Internet Explorer. Microsoft's deliverability found out about this at the same time the general public saw the press release a couple weeks ago - and he doesn't know why this decision was made by the Outlook team.

Ryan posted his notes on the Email Days blog: part I and part II.