Parsing email addresses is hard. You are mistaken if you think no "," can occur right of the "@" (which "@" do you mean, BTW? There can be many). foo@example (,) . (,) com is a syntactically valid email address.

There are a few CPAN modules out there that parse email addresses for validation. RFC::RFC822::Address uses Parse::RecDescent to validate addresses to the spec.

-- Abigail