news/mail client and the text borders

[Davide Baldini <baldiniebaldini@gmail.com>]

What software do you use for mail/news?
I see all your messages are proudly well formatted and perfectly fit in
pages of 80 columns, while I have to push return each line. If i forget, 
lines gets splitted in my window but then when i send it out i
see the big mistake...

is there any margins setting? I use icedove (thunderbird 3.0.11)