Excerpts from internet.ietf-822: 9-May-91 Re: lines, SMTP, ... Einar
Stefferud(_at_)ics(_dot_)uci(_dot_) (1722)
If you don't care what your text looks like on my 79 character
display, then go ahead and make your lines 80 or 81 or whatever number
of characters long you might wish.
Actually, Stef didn't mention this, but some mail transport agents will
wrap lines over some number of characters (commonly as low as 120,
occasionally even 80). So if you CARE about how your lines are wrapped,
you should do it yourself before some "smart" mail transport program
does it for you.