Public mail folder can't be recreated after deletion through web clients

[mrmarkuz]

A public mail folder can be deleted from a web mail client like Roundcube or SOGo by a user with "full control" permission.
Webtop is not affected as it does not allow removing public mail root folders.
The removal from a web client does not remove the sqlite database entries in the "addresses" and "destmap" tables. The creation of a new mail folder using the same name as the deleted one throws an error "Address already exists".

Steps to reproduce

• Install Mail and (Roundcube or SOGo)
• Create a user "testuser"
• Create a public mail folder "testfolder" and set permissions to "full control"
• Delete the public mail folder from Roundcube or SOGo
  
  
• Create a public mail folder "testfolder"

Expected behavior

The public mail folder is created.

Actual behavior

The public mail folder can't be created. A validation error is shown: "Address already exists"

Components

• Mail 1.6.4

See also

• Discussion https://mattermost.nethesis.it/nethserver/pl/8g1qoaamsjrodpw6p4bn6u941w