Well, seems there was a misunderstanding. I read your initial sentence as something technical (Broker_Addon has to be active all the time...), while you meant it as being simply impractical and beside the point.Now don't you think having a Broker_Mail-type addon that only loads and displays when you first visit the mailbox VERY silly? Postal only loads when you first visit the mailbox if the user uses AddonLoader. The point of the addon is to tell you when to visit the mailbox, not to visit the mailbox first to tell you when to visit the mailbox.
As for it being VERY silly, not everbody might use AddonLoader (even if they probably should). But then again, I'm not the one requesting or needing it, and it's your addon, so shrug.