|"if you want something more from your email program"|
Possibly a hasty statement because I believe that mostly the rest is glitz, such as:
Attaching pictures via the cloud (which requires MS sign-in), Diaries, Contacts lists, organizers and such like.
All I want out of email is to send and receive them with or without attachments. I'm on Window 8 now and "Outlook Express" doesn't run on it otherwise it would be quite good enough for me. I've never tried Thunderbird but assume it is somewhat similar. I now use "Outlook" instead (from an old MS Office I had on CD) but I rarely use the extras and spent some time almost making it work as neatly as Outlook Express used to.
Then there is webmail if you like that sort of thing....
Always pop back and let us know the outcome - thanks