Answer: Try unchecking "Send Alert emails" on the Alerts Criteria page for the target database instead.

You can reach the Alerts Criteria page for each target database by going to the Monitor page for that database and clicking on the "Alerts Criteria" link at the top right. If you are monitoring multiple target databases, you have to go to the Alerts Criteria page for each database and uncheck "Send Alert emails" there.

There are four settings that appear on both the Foxhound Options page and the Alerts Criteria page

             Send Alert emails: x
  Email address(es) for Alerts: ...
            Use HTML in emails: x
Host[:port] for URLs in emails: localhost

The values on the Alerts Criteria page for each target database are the values that are used at runtime.

The values on the Foxhound Options page are default values used to fill in the Alerts Criteria page when monitoring is first started for a new target database. This is a one-time "fill in the values" operation for each target database; later changes to any of these four values on the Foxhound Options page will not affect any target database for which monitoring has already been started.

See also...
The Alerts Criteria Page
Foxhound Options - Email Settings