What email provider are you sending from? example of gmail imap settings >> support.google.com/mail/bin/answer.py?hl=ar&answer=78892
Under Settings>Actions>Action type = Send email >> i get the following screen, where i can enter settings
I'm another SambaPOS user, and haven't tried this myself yet, but I suggest you try to test your email settings from the computer via some local program like thunderbird or outlook, make sure you got the settings right, then post here and show us exactly what setting didn't work. (minus your username and password.. )