Tray Helper it's freeware, award winning application with many features (f/e: email checker, auto mail responder, anti-spam, popup-killer, event reminder and more).
There was a new version (4.5) released recently (November 1, 2004) with following changes:

- Added spell checker for e-mail composer (few national dictionaries are available).
- Improved auto-update utility.
- Additional improvements in international character conversions.
- Added ability to find messages in mail box folders.
- Removed few bugs and added some less important features.
- Some minor improvements in user interface.