rfe12276: Handle SMTP servers which violate SMTP SASL AUTH protocol

Some SMTP servers (notably The Amazon SES SMTP endpoint
(email-smtp.us-east-1.amazonaws.com)) violate the protocol rules on the
first server response.  Apparently other SMTP clients are tolerant of
this, so we try to be as well.

Change-Id: I5280fa6473e56b5c08188d2819db3271294bf62a