Systray notification when mail comes into inbox

is there a possibility to alter the systray-symbol of the deskapp, when unread mail / new mail is in the inbox. For example in Outlook the Outlook-symbol in the systray changes to a envelope, if mail comes to inbox.

If not yet built in, would it be possible to include this in future releases?

Would be nice.

Really no one who is missing that? (or am I missing some settings, which do the trick?)

For most of our users this feature seems like to be the killerfeature…