[boost] Returned mail: Data format error

Subject: [boost] Returned mail: Data format error
From: sean.farrow_at_[hidden]
Date: 2013-05-22 03:02:28

The original message was received at Wed, 22 May 2013 15:02:28 +0800
from seanfarrow.co.uk [86.198.252.36]

----- The following addresses had permanent fatal errors -----
<boost_at_[hidden]>

----- Transcript of session follows -----
  while talking to lists.boost.org.:
>>> MAIL From:sean.farrow_at_[hidden]
<<< 501 sean.farrow_at_seanfarrow.co.uk... Refused