You mean turn off sending an email when someone writes @Bob_Carpenter? Click your picture in the upper-right, click the gear, click on "email" from the LHS menu, then there's an option for "
Send me an email when someone quotes me, replies to my post, mentions my @username, or invites me to a topic" , if you turn that off the @ won't work anymore. There are a few other relevant options in there.
No... you mean people are sending you direct messages? That's silly, no idea how to turn that off.