Oscar,

I'd recommend getting a copy of the bounce message -- have them send it to
your Hotmail/Gmail, etc. Error codes in the message may indicate the
problem.  There are also sites that maintain info on email blacklists for
organizations that don't follow best practices for newsletters/advertising,
have their server set as an open relay, etc. 

I used to run into this a lot dealing with an internal exchange server and
outside clients -- 95% of the time it was an issue on the user's end such as
sending large attachments, blacklisted organization due to bad practices on
marketing/advertising via email, typos on email addresses, Outlook issues,
etc, and 5% of the time an issue with the company that managed our spam
filter.

Example: http://www.mxtoolbox.com/blacklists.aspx


Shaun Leininger, CCNA
Information Technology Professional
Department of Anthropology
517-884-0388


-----Original Message-----
From: Oscar Castaneda [mailto:[log in to unmask]] 
Sent: Monday, May 14, 2012 10:02 AM
To: [log in to unmask]
Subject: [MSUNAG] blocked IPs?

I have a customer that claims that her emails to our staff (with @[log in to unmask]
and @[log in to unmask]) addresses are bounced.
She used to be able to email us all the time until about one week ago.
Everybody else can email us fine. We have a decent traffic of email on daily
basis.

I am pretty convinced that the problem is particular to them. 
Nonetheless, I would like to have something more tangible to show them. 
I was wondering if I could find if they are being blocked from MSU. I
remember in the past reading somewhere of IPs or blocks of IPs that would be
blocked from MSU for security reasons. Is there a way of knowing what gets
blocked from msu.edu?


--
Oscar Castaņeda
Remote Sensing & GIS
Michigan State University