Despite all the security vulnerabilities over the years, the clunky interface, and the near-glacial pace of improvements to the program, I still use Microsoft Outlook as my sole email client. And I love Outlook.
The tech circles I travel in are disproportionately weighted towards users of Mac OS and Linux, and the few Windows users I know are fairly anti-Microsoft in their beliefs, with many of them specifically citing Outlook in their list of reasons they hate Microsoft. So it probably bears explaining why it's my email platform of choice.
Well, actually, that does explain it: It's a platform. In a way that no other email client except Mozilla Thunderbird does, Outlook lets you extend and customize the application's capabilities. On my laptop alone, I've got plugins for Plaxo, SpamBayes, Microsoft's own Business Contact Manager, the indispensable NewsGator, and LookOut. I also used to use Cloudmark's SpamNet.
Of course NewsGator is important to me, since following syndication feeds is a big part of my job, but Lookout bears a closer look. About a year ago, I made one of my most uninformed tech posts ever, where I suggested RAM speed vs. hard drive speed could improve search result times. Thanks to my smart readers, I learned the secret is indexing, and that shoddy performance in desktop search is a result of poor indexing. Lookout proves this assumption, offering blisteringly-fast search of the gigabtye-plus store of email that I keep with me on my laptop.
Now, of course, Microsoft shouldn't have made Outlook's search so slow and assy in the first place. But I have a way to fix that, with an efficiency and integration that none of my Mac-toting friends can get in Mail.app.
Just as importantly, there's probably 50 people who make a living off of the Outlook plugins I've listed above. And that doesn't count the dozens of other add-ins available, or the excellent resources like Sue Mosher's Slipstick Systems site, where I've been finding out how to fix and extend Outlook for about 7 years.
Plaforms, people. Platforms, not programs.