Given

> dig turbojet.com.hk MX

;; QUESTION SECTION:
;turbojet.com.hk.               IN      MX

;; ANSWER SECTION:
turbojet.com.hk.        3083    IN      MX      10 smtp.turbojet.com.hk.
turbojet.com.hk.        3083    IN      MX      20 relay.incnets.com.

and

> telnet smtp.turbojet.com.hk smtp
Trying 203.80.224.23...
Connected to smtp.turbojet.com.hk.
Escape character is '^]'.
220 CheckPoint FireWall-1 secure ESMTP server
ehlo iota
250-Hello iota, pleased to meet you
250 SIZE
mail from: <>
250  <> ... Sender ok
rcpt to: <e+trial@turbojet.com.hk>
550 Mailbox unavailable.
quit
221 Closing connection

describe why an email from an SMTP-compliant mail transport agent will still reach the respective mailbox.
Comment on the efficiency of the current setup, and give a recommendation for improvement.
Bonus question: Analyse the email-address with regard to the so-called user + detail syntax of a popular MTA — can you make an assumption which other email addresses will likely be valid?

Responses[1]

Posted by Volker Stolz on 08 September 2009 15:38:00 HKT #