Found a fix for mine...
When going from 4 to 4S, you have to enter 2 passwords:
Incoming Mail Server is one the first mail account page, the one where you can toggle the account On or Off.
Scroll down to Outgoing Mail Server .... see the arrow to the right?
Clicking it brings you to a SMPT page, where you can activate one or more outgoing servers by clicking on, for instance:
and entering your password again for that account.
Account will be verified & voila!
Ok I think I may have a solution..this is what I tried and it worked.
go to :settings
then to the email account thats unable to send
then at the bottom ADVANCED
then near the bottom there should be a S/MIME turn it on
this is what I did and it worked !
By the way I was having problems with my hotmail account. I never had a problem with my Gmail