This can (optionally) contain data showing how messages have been handled (eg deleted, moved, etc)
Note that this logs commands sent to VPOP3's message store, NOT commands sent by the user, so it may not match what you think is happening. For instance, if a user deletes a message, you may see a copy to another folder (eg 'Trash'), then a bit later a message delete, then a bit later a message purge/expunge. That is how the 'delete' operation is actually performed in the background.