Why do mail server care about how long a line is? Why don't they just let the client reading the mail worry about wrapping the lines?
telnet smtp.mailserver.com 25
HELO
MAIL FROM: me@foo.com
RCPT TO: you@bar.com
DATA
blah blah blah
how's it going?
talk to you later!
.
QUIT
Edit: wrong.
However what most mail programs show as sender and recipient is neither, they rather show the headers contained in the message.