SMTP>> RCPT TO:<userx@test.ex>
SMTP>> DATA
cmd buf flush ddd bytes
+sync_responses expect mail
SMTP<< 250 OK
+sync_responses expect rcpt
SMTP<< 550 NO
+sync_responses expect data
SMTP(closed)<<
Remote host closed connection in response to pipelined DATA
error for DATA ignored: pipelining is in use and there were no good recipients