Tor and Thunderbird: Outgoing Email Unsafe?

[Job]

Hello,

I just got Tor to be safer online and used the Tor-button to 
automatically confugure Firefox and Thunderbird for Tor.
In Thunderbird however I have to exclude the server I use to SEND emails 
from being handled by Tor.

Maybe I am wrong but doesnt this defeat the whole purpose of Tor? Cause 
if my outgoing email is not handled by Tor the receives can still see my 
IP and all the other data and so can easely identify me.
The most essential thing is to have the outgoing emails handeled by Tor 
so the receiver can see my private information right?

How do I set thunderbird in such a waythat the receiver of my emails 
wont be able to trace me or see my private info(IP etc etc)?