The POP3 and IMAP protocols offer 2 methods of accessing the same information. You can use either or both protocols with no ill effect. Your device settings do not change our server configurations. Here are the fundamental differences in the protocols:

IMAP does not store email on the local device. This means that your email archive is the mail server itself. The consequence of this is that over time you will use a very large space storing all your old email. Also, deleting an item via IMAP will delete the item from the server forever. You need to be careful not to delete items via IMAP prematurely.

POP3 retrieves mail from the server and stores it locally. You can set your POP3 device to keep mail on the server for a specific length of time before deleting it from the server. Because mail storage is a separate function from mail deletion, the server only needs to store items for a brief time and server mailboxes can be smaller. The consequence is that messages deleted via POP3 will not be available to other devices which may access the same account. The solution is to set deletion time more than 1 day from the time a message is read. That will leave a copy on the server for a Blackberry device or any other device.

The DreamWeaver/Contribute suite uses a versioning scheme that stores a ".LCK" file on the server whenever a file is checked out. The file can be seen with any ftp client or from File Manger in CPanel. It will have the same name as the locked file plus .lck (i.e. index.html.LCK). Simply delete the file and it will be accessible to all users working on the site.