I attached a new sendmail patch. This one adds:

  explicit close of stdin after writing the message to sendmail

  wait for the sendmail process to finish

  check the return code. If it's 0 or 75 things are ok (75 indicates
      the email 1s queued according to the man page for sendmail
      I have). If it's any other exit code, raise MessageSendError
      with exitcode and stderr text.

Do we want to try getting this in the next release?