Utilities: List Settings: Automatic Maintenance: Purging Archives
Keep Archived Messages for How Many Days
This setting determines how long archived messages will be saved. Saving a message in the archives allows it to be read at a later date.
By default, your list is set to 0 (zero), or to keep archives indefinitely. If you set the list to not keep archives, no archives will ever be saved. This is the opposite of setting the list to 0 (zero).
Not saving archives conserves disk space.
Note: If you disable archive saving completely, users will no longer be able to receive digest versions of the mailing list, and duplicate messages will not be removed.
If you want your users to be able to receive digests, but do not want to keep archives, set the Archive Messages to Enable Merge Mailings setting to "Yes," and set Keep Archived Messages for How Many Days to "1". See Utilities: List Settings: Basic Information: Enable Features to save archives.
Keep How Many Messages Archived
This setting determines how many messages from the list will be saved in the archives. For example, a setting of 10 means that the previous 10 messages will be saved in the archives. Any old messages beyond the most recent 10 messages would be automatically removed.
By default, your list is set to 0 (zero), or to keep archives indefinitely. If you set the list to not keep archives, no archives will ever be saved. This is the opposite of setting the list to 0 (zero).
Keep Mailing and Clickthrough Data for How Many Days
This setting determines how long outgoing mail to your list is saved. Delivery and clickthrough data is only available for saved mailings. Increase this setting if you will need to refer to this data in the future.
Note that performance may decline if you keep mailing and clickthrough data for a very long time for many of your lists.
More
1. Utilities: List Settings: Automatic Maintenance
1. Utilities: List Settings: Automatic Maintenance: Error Mail Handling
2. Utilities: List Settings: Automatic Maintenance: Purging Inactive Members
3. Utilities: List Settings: Automatic Maintenance: Purging Archives