I don't think there's a service that will do this.
Are you really convinced that you're spending too much time on your play email account? If so don't you think you would have stopped? You should use an Internet usage monitoring program so you can see for yourself how much time you're really wasting there. Perhaps the shock will give you the self discipline you need!
Ultimately it is self discipline you'll need since if you really want to you can bypass any limitations you attempt to impose on yourself.
Of course if you're wasting time at work, you can approach your system admins and explain the problem you're having to them and see if they can block the problem sites for you. Sure, if you really wanted to you can get around this too, but maybe knowing that other people (at work, no less) know you have your problem you'll be able to control yourself.