Scenario:

  • 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.

Technical details:

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.

Workaround:

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.