Hello David -- Since I see no other relies as yet, I will take a shot
at your question.
First, if you read RFC821/822 very very carefully, you will see that,
no matter how you might represent locally lines in your internal files
in your UA, when you put the text on the line with SMTP, it must have
each line ended with a <CRLF> and nothing else. If the eceiving end
does not like this "transfer syntax" for its own local store
conventions, then it is obligated to translate the
<end-of-line--new-line>
encoding to be what it wants internally.
This is one of the many protocol rules that make things interwork
between dissimilar systems. The entire interworing agreement rests on
the ability for everyone to always put these objects "on the wire"
with the same syntax so it can be unambiguously decoded by the
receiving systems.
Also, SMTP requires that lines must be less than 1000 characters long,
but common courtesy suggests (not written in the standards) that you
make them less than 80 characters in order for them to "look nice" on
all recipient display screens. Many systems and terminals fold lines
after the 79th character on the line.
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.
This part of the "protocol" is like the unwritten, but widely accepted
human protocols that call for speaking clearly so other can understand
what you want them to understand, or using visible ink in your writing
pen, or writing in a font that is large enough to see without a
microscope, etc, et al. No magic here, just a little common sense.
Does this answer your questions? Cheers...\Stef