I happened to think that you can also use System Manager to get a report that will include all messages, not just new ones. This is assuming you use Exchange for your mailstore. In System Manager, drill down to the Mailbox Store and click Mailboxes. You will see a list of all mailboxes which includes the number of items in the box. You can right-click Mailboxes and export the list to a tab or comma-delimited file.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...