This purging interval is also relevant for the domain mailbox agents under: MailEnable Management > Right Click on the Post Office >Properties>Agents Tab
The clean-up options for a post office are configured in the post office properties.
Enable Mailbox Clean-Up Agent on this server
Enables the polling and actions. The settings that have been configured for the Bad Mail or Quarantine folders are displayed in this screen. Also for the domain mailbox cleanup agent as mentioned in following section.
Polling interval for purging
Number of minutes between when the service will purge emails. In order to perform a purge, the service needs to examine each folder, and possibly emails for each user, which can be both time and resource intensive. It is recommended to time this so that it occurs only at off-peak times every few days, depending on the number of users configured on the server.
Properties (Folder clean up)
This can be set not to delete any unread messages and delete messages in folder over a specified number of days old.