220 mailgate.mydomain.com ESMTP Postfix (Ubuntu)
ehlo mailgate.mydomain.com
250-mailgate.mydomain.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<yiannis@domain.com>
250 2.1.0 Ok
rcpt to:<guser@gmail.com>
451 4.3.0 <guser@gmail.com>: Temporary lookup failure