Mail.appetizer has been around for some time, and I find it to be invaluable for dealing with email more efficiently. How many times have you been working in another application only to see the little red indicator show up on the Mail.app icon? In order to see if what you received is worthy of your attention, you have to switch over to Mail and click on the new message. That’s just too much effort to find out if you need to deal with a new message immediately.
Mail.appetizer will display a transparent window that displays the message no matter what application you’re in. You can configure the window to disappear after a certain number of seconds. I use 2 seconds which is long enough to see what’s up and short enough to disappear quickly and not be annoying. You can also customize the information displayed from the message, the level of window transparency, and other details illustrated below.
I highly recommend this little app as it’s a major time saver and providese a ton of convenience over chasing your email down blindly.
Mail.appetizer Preferences
Mail.appetizer Sample Popup Window



