Help with Preference pane DNS settings for Mail

I have a mail (not Apple Mail) issue with my Entourage Mail. I keep getting
the following error message and I have verified the server settings in my
mail accounts are correct for ATT that uses pop.att.yahoo.com. I manage to
get mail most of the time but I still get the following error message:

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Error Description

Error:

Entourage cannot find the server. Verify the server information is entered correctly in the Account Settings, and that your DNS settings in the Network pane of System Preferences are correct.

Explanation:

Could not retrieve mail

Error: -1370
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My System Preferences/Network/Advanced/DNS point to my 2wire Gateway combo
modem/router. The router is set for Automatic DNS. I tried changing it to manual
and it did not works any better.

If I change the DNS setting in the preference pane in OS X, will it really use that
DMS address and bypass the router?

I played around with the namebench utility
http://www.macupdate.com/info.php/id/32784/namebench and each time you
run it, namebench makes a better recommendation - saying something is faster
than the previous recommendation.

I am lost on what I need to do correct the Network pane of my System Preferences.

Should it point to the router or to good DNS?

I do not think this is a Microsoft Entourage issue.

Have others seen this issue or is unique to my setup.