This would be a start: Check for presence of at symbol (@). Check for a period. Obviously doesn't ensure the @ is before the period. But this might get the most invalid email address formats. Suppose you could cheat and have two properties (who, wherever and reference the properties who@wherever). Verify that wherever has a period in it.
Not ideal...just spitballing.
Additional idea...SQL sorcery could probably achieve what you are trying to do. Unfortunately my SQL abilities go as far as SELECT * FROM __ WHERE __ ORDER BY