The Mail Shield is far from redundant.
Personally I think it a mistake to uninstall the Mail Shield even if don't use an email program, but use web mail viewed through your browser. In fact I would suggest you leave it installed as it isn't using resources unless it is actually running and I would go further to suggest that you set the sensitivity to High.
The reasoning for this is, if you have a trojan spambot (they have their own SMTP program), which has got past your defences, either undetected or hidden; then your first indication could be the alerts from the Mail Shield of this activity.
If the User only uses webmail then the Mail Shield wouldn't be consuming any resources until it is active, which it shouldn't be unless something is using the monitored email ports.
