You can check following one by one:

1. From Administration | System | System Behavior, "Use Exchange Server Integration" field should be set to no. You must reffer Administrator guide if you were using Exchange server Integraion before.

2. In IE check if Icon is missing? Go To: Administration -> E-mail and Documents -> Documents & Reports Configuration check if "Allow ActiveX Document Drop" filed should set to Yes, some times for IE users it restricts the Icon under preference tab.

Let me know if any of above is helpful !

All the best!