Maileater is failing with a core. Knowledge tools notifications are not working.
In stdlogs errors point to "Attribute 'upload_path' is empty for usp_servers (id=1001)".
Here are some errors that you might see in stdlogs:
"pdm_maileater_nxd 1430508 FATAL pdm_maileater_nxd.c 1811 (integer)24 (-1) in Mailbox initialization method got_doc_rep_attr_vals"
"spelsrvr 8415672 ERROR doc_rep.spl 688 Error on dob_by_id() for usp_servers (id=1001). NOT FOUND"
"doc_rep.spl 708 SIGNIFICANT Attribute 'upload_path' is empty for usp_servers (id=1001). Consider entering a value via Web UI Servers form."
According to the errors in stdlog it is looking for a repository which is linked to server id 1001 in usp_servers table.
Check the table usp_servers to see if there is a record with id 1001. Most probably that record doesn't exist hence the errors in the stdlog.
To fix this problem you would need to extract Document_Repository table or check the table directly on your database.
Check for the field 'Servlet Server'. if it is pointing to id 1001 that is wrong as that server doesn't exist in your usp_servers tables.
Recommendation would be to update the Repositories via web interface by going to Administration\Attachment Library\Repositories. Right click on the Repository and edit. Recycle services.
This should fix the errors in the stdlog.