Use case: when you don't want your email hanging around on the other guys server. Ex. sending credit card information to a hotel. You want them to get it, ie. y

Use case: when you don't want your email hanging around on the other guys server. Ex. sending credit card information to a hotel. You want them to get it, ie. you trust them enough, but you can't trust their email security for the next 4 years. Think how someone like General Patreaus could have benefited! He trusted Broadwell (perhaps his main mistake), but unfortunately for him the email hung around long enough for the FBI. :)) Also, docs say email is destroyed as soon at is read. No 7 days (couldn't find that).