"AFAIK there is no real alternative to Outlook for handling email" - What do you wish the programme to do?
My own e-mail needs are very simple, and Opera handles them well enough both under Windows and Linux (I fell out with Thunderbird, can't remember why). Your needs sound more complex, but if you can explain what they are then someone might have an answer.

I have one old laptop still on XP, not powerful enough to upgrade to W7 so I expect I'll flip it over to Linux in a while. Sadly I don't think it will boot from a USB stick, so I'll have to couple up a DVD drive for the changeover.

Pity about XP getting killed off, but it can't be helped.