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<contrib-admin@crux.nu>: host mx-gtw1.dnsnoc.net[213.132.114.80] said: 450
    4.7.1 Client host rejected: cannot find your hostname, [78.129.137.222] (in
    reply to RCPT TO command)
Reporting-MTA: dns; boston.localdomain
X-Postfix-Queue-ID: E74C4A60700
X-Postfix-Sender: rfc822; dm@archlinux.info
Arrival-Date: Wed,  1 May 2013 14:41:12 +0100 (BST)

Final-Recipient: rfc822; contrib-admin@crux.nu
Original-Recipient: rfc822;contrib-admin@crux.nu
Action: failed
Status: 4.7.1
Remote-MTA: dns; mx-gtw1.dnsnoc.net
Diagnostic-Code: smtp; 450 4.7.1 Client host rejected: cannot find your
    hostname, [78.129.137.222]