See Mail::RFC822::Address which has "the" regex for valid addresses. Right off I see that yours has one of the common problems that tend to tick me off, specifically disallowing "foo+identifier@example.com" style addresses (which lets me have one "foo@example.com" address but give out different "+identifier" tags to different people so I can label/tag/filter/toss accordingly).

Update: Also see RFC::RFC822::Address for a Parse::RecDescent based parser rather than a regex.