In the recent past, I have been using solely Ubuntu (12.04 LTS) as my primary work machine. And I use Thunderbird for my mail and calendaring needs. It integrates beautifully with Exchange server.
But what surprised me pleasantly was this:
I had typed in “Please find the resume attached” in the email. Nice touch Thunderbird. For a person who has been burned multiple times by missing to attach files to emails, this comes as a refreshing surprise indeed.