...to the client address as this frees the RCPT strings to contain
just an email address and by passing the test number into curl as the
client address remains consistent with POP3 and IMAP tests as they are
specified in the URL.
If the mail sent during the transfer contains a terminating <CRLF> then
we should not send the first <CRLF> of the EOB as specified in RFC-5321.
Additionally don't send the <CRLF> if there is "no mail data" as the
DATA command already includes it.
