I just check that the string contains at least an @ character. That ensures that we're not rejecting people with uncommon patterns in their email address and ta

I just check that the string contains at least an @ character. That ensures that we're not rejecting people with uncommon patterns in their email address and takes very little time to design, develop and test. In a project we're doing something fancier: we check the result of sending mail and store it in the database record for the account (Mandrill notifies us on a webhook.) Then we might take actions for bouncing addresses. The actual impact on the project has been zero so far.