Making changes to Inbound Mail Action Settings and then attempting to go back in and look at these settings throws an XML document error.
Possible corruption in the XML stored in the database.
Take a full back up of your Service Desk database.
Then run the attached script UpdateActionSettingsToOOTBValue.sql to restore the action settings back to the default out of the box settings.
LANDesk Service Desk 7.3.2