This problem arises from use of the Verizon Wireless Sync software. 
The Verizon Wireless Sync software syncs your Palm Treo email with the  
Push system Verizon uses to forward the mail to the handsets. 
There is an option in the preferences for the Wireless Sync program on the  
Verizon Treo 650 that allows the Treo to sync with other conduits.

To access this preference, on the phone:

1. Go to Wireless Sync
2. Open Connection Settings menu
3. Tap Advanced option on page bottom
4. Check Enable Other Sync Apps

You should be able to perform a successfull sync.


Here are two related articles about this issue.

Mark/Space Inc (Missing Sync):
       http://www.markspace.com/support/index.php?x=&mod_id=2&root=89&id=2430

Apple:
       http://docs.info.apple.com/article.html?artnum=302064