If we put the string in the message body (application/x-www-form-simple)
and treat it as binary it shouldn't matter how long the line is like it
does for the URL part. MIME will take care of the rest (e.g., if it
needs to go through a mail gateway it could get encoded as BASE64).
BTW: I vote we start explicitly using:
Content-Transfer-Encoding: BINARY
In the HTTP/1.0 protocol. This will make it easier on mail based
transports to do the right thing.
multipart/mixed we can worry about later.
--sanders