Exim's BSMTP interface will indicate the SMTP response to the exchange;
actually use it rather than assuming all errors are 400-class soft ones.
Tolerate $transaction->header returning undef (since it evidently can under
some conditions).
Convert a few errant tabs to spaces.
Fix vi modeline.
Signed-off-by: Robert <rspier@pobox.com>
3889821d16