Resource web site to find current network conditions on the Internet.
I run a mail server and sometimes see high amounts of connection
failures at ISPs. Is there a web site(s) that are good resources to
determine if hotmail, yahoo, or others are having a high amount of
email sent to them and therefore their email servers are getting
overloaded?

At first glance, there does not appear to be anything specific to mail
servers, but this site may be helpful:

http://www.internettrafficreport.com