After you reply to a message, or you forward it, the message is downloaded again to the POP3 client when you reconnect to a mailbox that is hosted by Exchange Server 2007

Consider the following scenario:

• Your mailbox is hosted on a server that is running Microsoft Exchange Server 2007 with Service Pack 1 (SP1).
• You use a POP3 client to download a copy of a message that is in the mailbox. A copy of the message remains on the server.
• After the message is downloaded to the POP3 client, you reply to the message, or you forward it by using the Microsoft Office Outlook Web Access (OWA) client or by using an Outlook client that is in online mode.

In this scenario, the message reply or the forwarded message are downloaded again to the POP3 client when you reconnect to the mailbox and download new messages.

Note An IMAP4 client may experience the same issue.

The status of a message changes when you reply to it, or you forward the message. When the status of the message changes, the properties that a POP client or an IMAP client use to verify a unique message are updated. This behavior causes messages that are replied to or that are forwarded to be treated as new messages by the POP client or by the IMAP client. Therefore, the message is downloaded again if when you use the POP client or the IMAP client to access the mailbox.

To resolve this problem, download and install Exchange Server 2007 Service Pack 2. For more information about how to obtain the latest Exchange service pack or update rollup, see the following Exchange Help topic:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.