When messages are deleted they will be moved to the Deleted Items Folder. They will remain there (and available for viewing or return to any folder) until either messages are killed (permanently deleted) or the Deleted Items Folder is purged.
Emptying of the Deleted Items Folder will occur automatically each time MailCOPA is closed if configured to do so in Configure Preferences General Further information here.
The Purging of the Deleted Items Folder can also be configured in the Folder Properties if you wish - however, any settings there will be overridden by the setting to Empty Deleted Items on Exit (Configure Preferences General), in which case the controls on the purging tab for the Deleted Items Folder will be disabled, and ALL messages in the Deleted Items folder will be deleted on exit.
Other folders will be purged according to the general settings in Configuration Preferences Purging, (for further details see here) unless these have been over-ridden in the Folders Properties.
Purging can also be undertaken manually (in keeping with the general and/or individual settings) at any time - Utilities Perform Mail Purge.
Messages may be completely removed in one step - Message Kill Message (also available from the right-click Context Menu for a message). Note that you will receive a warning that this will permanently remove the message(s) unless you have checked the option in Configure Preferences General Switch Off kill message warnings.
Once messages have been purged from ANY folder (including Deleted Items), or Killed, all pointers to them are deleted though the actual contents will remain in the database, but now marked as part of the free space within the database, which will be used to store messages later received.
Any message contents not so overwritten may be recoverable by the Intervations developers, but this cannot be guaranteed.