Thunderbird for me all the way, in fact been using Thunderbird predecessors Netscape email till it changed to Mozilla and finally Thunderbird a 10 year loyal fan
I'm not using any software. I'm using Gmail and Hotmail. Once i tried to configure the MS Outlook but i failed and then never tried it again. -Rocky!
Nowadays a lot of controlpanel allows you to create a reg key, just setup your email account, create the reg key save and click on it and you have your Outlook configured. It is in Cpanel and Directadmin, not sure of the rest but it does make life easier for a lot of people.