Fortunately, you can still find out about Mac OS X Mail's hidden activities.
See What Mac OS X Mail is Doing in the Background
To watch background activities in Mac OS X Mail:
- Select Window | Activity (or Window | Show Activity Viewer) from the menu in Mac OS X Mail.
If you want to get rid of the Activity Viewer window again, either close it or select Window | Hide Activity Viewer from the menu.
And if you refer to it often, you can also toggle the Mac OS X Mail Activity Viewer by pressing Command-0.

