Test Prefixes

Just a quick question.

I know for instance in the mission info if you type in:
Title
it will allow users to link to that web site via a click.

For example:
RealmWars in a mission info
would allow users to go to the Realm Wars site if they clicked on it.

Does anyone know what the command to use an email address
in there would be? I've tried a couple of different things but have
yet to get anything to work. The command tries to connect
to a website and doesnt provoke an email window to send to a user.
Any ideas would be helpful.