select email from loginuser where patindex ('%[ &'',":;!+=\/()<>]%', email) > 0 -- Invalid characters or patindex ('[@.-_]%', email) > 0 -- Valid but cannot be starting character or patindex ('%[@.-_]', email) > 0 -- Valid but cannot be ending character or email not like '%@%.%' -- Must contain at least one @ and one . or email like '%..%' -- Cannot have two periods in a row or email like '%@%@%' -- Cannot have two @ anywhere or email like '%.@%' or email like '%@.%' -- Cannot have @ and . next to each other or email like '%.cm' or email like '%.co' -- Camaroon or Colombia? Unlikely. Probably typos or email like '%.or' or email like '%.ne' -- Missing last letter