Well if the version installed is the version in the article (i.e. vers 7.0) - maybe the best course of action would be to actually remove and bypass GSE701 and go for MSME 7.6. You could use Add/Remove to remove existing and use How to manually remove GroupShield 7.x for Microsoft Exchange (KB51894) to clean up any remnants left behind.
MSME 7.6 and its Patch 1 are avaibale for download at McAfee Site with your Grant Number.
On whitelist - Access the GSE console - Policy Manager - Gateway - Master Policy - AntiSpam - Core Anti Spam settings section click "Edit" - select "Mail Lists Tab" - select "Whitelists" - In Whitelisted Senders box put in *@thatdomain.com click add - Save and Apply.