I would have preferred to not have use_crlf, but dovecot expects the
"virtual size" (bytes that will be sent) in W=xxx. The obvious thing to
do that would be ${eval:$message_size+$message_linecount+1}, but
$message_linecount (unlike $message_size) is not updated when headers
are added etc., so that does not work. I wanted make up a fix for that
in Exim, but did not get around to do it. Hm, maybe filing a bug report
would be a good start. :)