450 try later
550 no such user
Which, if any, of b, c, and d get retried? Why or why not? What if
the 554 were a 450?
My take FWIW, is that none should be retried because the data is
rejected (probably based on content analysis e.g. spam or
virus). If the data response were a 450, a+b+c should be retried.
But 554 can mean all sorts of things. Maybe it was a content failure,
maybe there was some screwup storing the mail. Or let's say it was a 552
which can mean mailbox full. Now what?
Like I said, this gets really twisty.
John Levine, johnl(_at_)taugh(_dot_)com, Taughannock Networks, Trumansburg NY
"I dropped the toothpaste", said Tom, crestfallenly.