- You have a mailbox on the Exchange server.
- You have a POP email account configured for the Exchange mailbox.
- You have a BlackBerry device activated which is connected to the BlackBerry Enterprise server.
When you click the Send/Receive button in a mail client with the POP account, you get duplicates and triplicates of each downloaded message.
This is a known issue that has been reported to RIM and most likely will be fixed with one of the next BlackBerry Server updates.
It seems that BlackBerry server clears the download flag used by the POP protocol to define which message was downloaded. Therefore each message is downloaded again.
Create an IMAP/Exchange account instead of the POP account, or use Outlook Web Access to check your email.
Read the Knowledge Base article on How Can I Connect To My Exchange Server Using POP Or IMAP? for more information.