Multiline result codes
----------------------
RFC821 Appendix E:
  The format for multiline replies requires that every line,
  except the last, begin with the reply code, followed
  immediately by a hyphen, "-" (also known as minus), 
  followed by text.  The last line will begin with the reply 
  code, followed immediately by <SP>, optionally some text, 
  and <CRLF>.

  In many cases the sender-SMTP then simply needs to search 
  for the reply code followed by <SP> at the beginning of a 
  line, and ignore all preceding lines.


The current Ack() function in sendmail.c only looks at the
reply code on the first line of a multiline reply, rather
than the reply code that is followed by <SP>.  I don't know
if there is any way this could be a problem, but it can't
hurt to have it documented.