Strange problem, our Exchange server appears to be rejecting emails from yahoo after they have been through our anti-spam provider. This only seems to happen with yahoo address. Even more strangely we have multiple accepts domains with many users having multiple aliases, I've sent a test email to myself from a yahoo account and it has delivered to one domain but not another. I also included my gmail account which delivered no problem.
Failure notice as follows:
Sorry, we were unable to deliver your message to the following address.
Remote host said: 550 Not accepted. [BODY]
--- Below this line is a copy of the message.
Received: from [126.96.36.199] by nm21.bullet.mail.ukl.yahoo.com with NNFMP; 05 Dec 2011 17:03:16 -0000
Received: from [188.8.131.52] by tm2.bullet.mail.ukl.yahoo.com with NNFMP; 05 Dec 2011 17:03:16 -0000
Received: from [127.0.0.1] by omp1014.mail.ukl.yahoo.com with NNFMP; 05 Dec 2011 17:03:16 -0000
Received: (qmail 18138 invoked by uid 60001); 5 Dec 2011 17:03:15 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1323104595; bh=rmj+TcPW/MYtQW9tXokSDaxYgmB2363WHRQS+MdvpfM=; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=RcnKcfGA2aEvhMM5XDqiatmtddhUzoyu6yqax1EbYy+TBpz8r0xpm3X+jlq4DlkHjn+Of4MvveDJKDq79w4jmBpCivkCKOAlM86rIzgl/cqIJVpz5dSJ+zEddfU/wv6LP6Ud+i01IlNvkoat6knk9pbCHm5J6B8g+e4CMYkYpMk=
DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws;
Received: from [xxx.xxx.xxx.xx] by web28107.mail.ukl.yahoo.com via HTTP; Mon, 05 Dec 2011 17:03:15 GMT
Date: Mon, 5 Dec 2011 17:03:15 +0000 (GMT)
From: User <email@example.com>
Reply-To: User <firstname.lastname@example.org>
Subject: Test this one
To: "email@example.com" <firstname.lastname@example.org>,
Content-Type: text/plain; charset=utf-8