After removing mailman as a Plesk component, services stay up.

[senthil]

Symptoms

• After removing mailman3 as a Plesk component, its services mailman3.service and mailman3-web.service
  may stay loaded, active and running.

Cause
Bug confirmed as PPPM-14815.
When it is fixed it will appear in our release log: Change Log for Plesk Obsidian

Resolution
As temporary workaround, manually stop and disable the services:

Code Select Expand

#systemctl stop mailman3 mailman3-web && systemctl disable mailman3 mailman3-web