SMTP always uses \r\n end of lines as it is required in RFC 822. When I cared about such things, my solution was to

every input line. This gets rid of trailing white space, all EOLN characters and generally works well in mixed environments. It might not be very unicode friendly, but that was never an issue for me. When you print it out simply

and you always have the local EOLN regardless of what your data was.

- doug