How can I crack MD5 hashed email addresses?

[oxguy3]

I am very new to hashcat, but I have a list of MD5-hashed email addresses that I need to crack. The emails are in all lowercase and it's safe to assume that the TLD is probably com, org, or net. Since its not possible to write rules simply using regex, how can I get hashcat (or one of the oclHashcats) to only check values formatted as email addresses? Thanks! (and sorry if my question is a dumb one)