Account-specific behavior in Mail.app?

Are there any plugins that let you set different "check mail" intervals for each account? I have two accounts that both get a good bit of mail (personal and shopping/public). I'm tired of constantly seeing I have new mail but having to open the app just to see it's not urgent. I'd love to be able to have the personal box checked every 5 minutes while the public one is just every so often (or even manual).

Any thoughts?