If VPOP3 is using a lot of disk space, the problem is usually that there is lots of data there, so it has to use the disk space.

In VPOP3 version 5 and later, all users' messages are stored in the database, so they will occupy space in the VPOP3\pgsql\data folder

In VPOP3 versions 3 and 4, users' small messages are stored in the database, so will occupy space in the VPOP3\pgsql\data folder. Large messages are stored in the VPOP3\_messages folder tree, so occupy space there

In VPOP3 versions 1 and 2, users' messages are stored in the VPOP3\<username> folder trees, so occupy space there

If you have message archiving enabled, then the archived messages are stored in the message archive folder (which may be VPOP3\_archive, but can be placed elsewhere)

If you are using the spam filtering in VPOP3, then quarantined messages are stored in the VPOP3\_quarantine folder

By default, VPOP3 will create daily database backups called DBBACK-x.DMP in the VPOP3 folder. These are backups of the database.

In version 5 and later, all messages are stored in the database, so the DBBACK-x.DMP files may be large, as they contain all the messages (plus other data) In version 3 and 4, the backups will be smaller, because they only contain a partial message backup (so you should also backup the VPOP3 directory structure separately)

You can move the database backups to another location on the Settings → Database → Backup page in the settings (see also, the handling database backups topic), but we strongly recommend that you don't disable database backups totally. Otherwise if there is database corruption for any reasons, you will lose everything

VPOP3 also stores lots of other data, such as logging data, statistical data for the spam filter, etc. In versions 3 and later, this is all stored in the database, so will also be backed up daily.