select email

from table_name 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 ? Typos .