I've recently started a new job as a PHP/MySQL web developer (and, as it transpires, the fixer of all things electronic and computer related) and as part of my contract they said I could use whatever software I wanted. Naturally I removed Windows 7 from the massively over-specced gaming PC they provided for me (?) and put Ubuntu on.
The other people in the office use Macs and, as it's a new company, the emails needed setting up. Since the parent company uses Exchange 2003 the choice for the Macs was obvious - Outlook. Which, after several attempts at configuration, wouldn't connect to the Exchange server.
However, on my free desktop Evolution with the MAPI plugin connected without issue - even allowing me access to the company directory!
Eventually I persuaded tech "support" to open port 143 for IMAP connections for the Macs so now everything is (almost) working as it should.
So, open-source product = 1, Microsoft product (connecting to another Microsoft product) = 0.
And obvious brownie points for me for pointing out the glaring problems with their IT infrastructure....
If at first you don't succeed, call it v1.0