Mail Server for "my domain" unreachable for too long

We have a very important client that frequently needs to send us email.  He, however, continues to receive error messages when sending them.  He is the only person I know of having these problems and I don't know why.  Any help would be appreciated.  The error message is below...

-----Original Message-----
From: []
Sent: Saturday, November 16, 2013 12:30 PM
Subject: Failure Notice

Sorry, we were unable to deliver your message to the following address.

Mail server for "" unreachable for too long

--- Below this line is a copy of the message.

Received: from [] by with NNFMP; 15 Nov 2013 18:29:09 -0000
Received: from [] by with NNFMP; 15 Nov 2013 18:29:08 -0000
Received: from [] by with NNFMP; 15 Nov 2013 18:29:08 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=s1024; t=1384540148; bh=oULWd5Oc04POxe6dC80x8Zojt5kICIticns5nqOJ3Y8=;
X-Yahoo-Newman-Property: ymail-3
X-YMail-OSG: r5uAZ08VM1mcfAOBsL.X1foq2qI4racZFOc_fLR3_E51i2C
X-Yahoo-SMTP: 9w_Wy92swBAx38f1eFCm0bGxEm7cONNyWzHXDNqE2Q--
X-Rocket-Received: from PPosner7lt (pposner@ with )
        by with SMTP; 15 Nov 2013 18:29:08
+0000 UTC
Who is Participating?
valmaticConnect With a Mentor Commented:
Have you tried dealing with the yahoo (swbell) postmaster. When in doubt is the way to go.
valmaticConnect With a Mentor Commented:
have you gone to and put in both yours and his mail server information and run the smtp tests, and checked for blacklisting?
tmartin40Author Commented:
Yes.  I have found several postings online stating yahoo (swbell host) is doing this to a lot of people but there no answers to the problem.
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tmartin40Author Commented:
I'm trying to reach out to them now.
Seeing this issue here as well. Monitoring this thread with interest.
tmartin40Connect With a Mentor Author Commented:
I have found multiple articles online about yahoo email having this problem.  Maybe it is just a Yahoo issue.
tmartin40Author Commented:
Well, it has been two days and I still have not received a response from email provider.
tmartin40Author Commented:
The problem still has not been resolved as I cannot get a response from  The problem, however, has to be on their end.
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