The problem with 1944 dates on incoming mail is mainly limited to AOL users.
The new server code is rolled out across the board so all
Emailer sessions will see the 4-digit date now.
Emailer should work "out-of-the-box" with AOL now.
Links for upgrades can be found here.
Check out Install Woes here.
1) Restart with extensions disabled (this will ensure that no Font patches are active).
2) Install a clean copy of Emailer, and update it using the 2.0v3 updater.
Try installing Emailer on another partition that doesn't have HFS+ , and then run the updater. Move over after updating.
Machines with DiskDoubler (actually AutoDoubler) on them, will get an error message when trying to upgrade to 2.0v3. The solution is to restart with extensions off, use the Expander Utility that comes with DiskDoubler to decompress the Claris Emailer folder, then run the upgrade.