If the Archive Messages box is checked, then VPOP3 will archive incoming and outgoing messages.
You can set the message archive store to any directory accessible by the VPOP3 service. Enter the path in the Main Archive Store Directory box. Note that you cannot use mapped drives. To use a remote share use the UNC naming convention - ie \\server\share\path. If VPOP3 cannot access this folder, it will queue archived messages locally until the remote path can be accessed.
Also, note that the VPOP3 service needs to have access to any shared folders - the VPOP3 service may be running as a different user from the currently logged in user, so you need to check access permissions carefully if you are having problems.
In VPOP3 v6 and later you can tell VPOP3 the username & password to use to access the main archive store directory if it is on a network shared folder. This is set in the Username to access Main Store and Password to access Main Store boxes.
This section tells you how many messages (and total size) are in the main archive store, and how many messages are queued up to be sent to the main archive store (if everything is OK, this will usually be a low amount)
If there has previously been a problem with VPOP3 accessing the main store, and it has now been fixed, then you can check this box and press Submit, and VPOP3 will send messages into the main archive store more quickly than usual. Note that this will place extra load on the server, so if your server is usually quite busy, use this with caution.
VPOP3's archive search facility can only search messages in the main archive store, so that is why you may want to do this.
The Don't Archive Spam box can be checked to reduce the number of messages being archived, but note that this may reduce the functionality of the archive for legal purposes. If a message is quarantined by VPOP3 it will not be archived if this box is checked. However, if the message is viewed or released from the quarantine, it will then be archived.
In VPOP3 v6 and later, you can instruct VPOP3 to rescan the archive folders and find any messages which are there, which are not currently indexed. Usually this is not needed, but if you have had a problem, and could only restore a partial backup or something, then this can be useful.