It is not a joke, 4000 mailboxes is a LOT and it has limited means t remove them. It is not about not wanting to help you, we have tried to help you numerous ways even sending tickets to psoft.
"Getting the List of Available Services
You may get the list of available XML services by typing in your browser:
http://your_cp_host:8180/your_cp_url_path/AxisServlet
where:
your_cp_host is your CP host domain (CP_HOST in hsphere.properties), and
your_cp_url_path is usually psoft/servlet if not configured otherwise in your Tomcat configuration."
When I connect to soap api I get the same error as showed in the link of checking HSPHERE services, “connection refused”.
If I was able to create 4000 mailboxes with soap api, Im sure it would be possible to delete, in case it were working in you server.
It should work in normal case, but yours is different with huge count of mailboxes. We will still investigate it and this is why your ticket is on hold.