How my mail notifier avoids interrupting me
For years, I've used a program called xlbiff to handle notifying me about new mail, and I have it set to check quite frequently. On the surface, this ought to be a really disruptive thing; new mail notification is widely held to be one of the best ways to yank your attention away from what you're currently doing. But in practice xlbiff doesn't act this way for me; it's far less interrupting than it sounds while still letting me deal very rapidly with important things.
(As a sysadmin, outright ignoring email is not an option for very long. Being interrupted all the time by sufficiently important things is part of my job.)
I believe that there's two major reasons why this is the case. First, xlbiff is just informative enough to let me make a decision to ignore the new email; in practice, seeing the author and the subject is enough to let me filter out almost all of the email I don't need to read right now. Anything less informative would force me to immediately do more checking in order to decide if the mail was important; anything more informative would take up more screen real estate (and might show me enough information for the mail message to be tempting).
Second, xlbiff is a dead end; it gives me no way to look at the mail further with simple actions inside it. If I want to actually read the email, I have to open up my full mail reading environment and get to it. This means that it is not easy to get distracted by reading new mail. Such distraction is not temptingly right at hand, only a mouse click or two away (or a keyboard binding or two away), the way it would be if this notification either was integrated into my mail reader or if the notifier could helpfully open my mail reader at a mouse click.
(The lesson I draw from this is that convenience is in some way the enemy of avoiding distraction. If you want to avoid the latter, you need to avoid conveniently fast and effortless ways of getting to it; instead, put some things in the way to slow people down and make them hold back.)
Oh, and the third reason is that xlbiff does not nag at me with any sort of persistent 'you have some unread messages' marker. Instead, it notifies me and then it goes away when I tell it to; it will only notify me again if new mail comes in. Persistent markers are a persistent nag, and sooner or later they will win the battle for your attention (or you will do something just to shut them up).
From this I can construct the platonic ideal of a terrible modern mail notifier: a persistent 'you have new mail' status icon in your notifier area, where the only thing you can do with it is click on it to open up your regular (IMAP) mail reader. This combines minimal usefulness with maximal distraction potential when you try to find out anything more about that new mail you have. Giving it a tooltip containing the author and subject of your new mail would be only a moderate improvement.
(Sadly, I'm sure that there are any number of mail notifiers that work just like this.)