WorkgroupMail does not download all messages when configured to
WorkgroupMail does not download all messages when configured to “Leave a copy of messages on the server”.
When configured to ‘Leave a copy of messages on the server’ WorkgroupMail will connect to the POP3 server at the ISP and query it to get the message headers of current messages. For each message, WorkgroupMail will extract the message ID and check to see if it has already been received. If it has then WorkgroupMail will not download it. If the message is older than permitted (WorkgroupMail setting) then it will be deleted from the POP3 server. New messages will be downloaded.
If more than one message with the same message ID is delivered to the POP3 mailbox then WorkgroupMail will only download the first one. The message ID should be a unique identifier and it is not permitted for multiple messages to have the same message ID. The consequence of this is that the message that arrives later will not be downloaded and it will eventually be deleted from the server.
When replying to a message in Outlook XP, the message reply can use the same message ID as the original message. If two replies are sent back, as may be the case when a read receipt and a written reply are returned, then only the first message will be downloaded. Note, the use of Read receipts under these circumstances will greatly increase the severity of this problem.
The best way to avoid this is to not use the setting ‘Leave a copy of messages on the server’, unless absolutely necessary. If you believe that a message has not been downloaded by WorkgroupMail then delete the file msgids.dat in the WorkgroupMail data folder. This will delete the record of previously downloaded messages. All messages at the ISP will then be downloaded with some obvious duplication. When the message in question has been received, remove the setting ‘Leave a copy of messages on the server’. On the next connection WorkgroupMail will delete all messages from the server.