How to validate the email field?

Hello all, We are doing a survey on the network performance at UAB. In the survey form provided to the users we are having an email field, which was declared as varchar(25). Because of that even some body fills like 'ah:#@fhjk-@///kjdfr' as their email address, our form is accepting it as a valid email field. So we want to apply some validation while the user submits that form. Can any one suggest us how we can apply this. Thanks and regards Chakravarthy K Sannedhi