Currently for every incoming mail a new user is created in deskpro.
Not only for each originating email address but also for each CC'ed email address and this leads to a lot of garbage in the user list.

Often an external user cc's many other internal or external colleagues to keep them informed. All these emails generate extra users in the CRM module which often are not linked to a company. Also incorrectly spelled email addresses are automatically generating new users.

As it result and after some period, a large amount of users in the deskpro database is mainly garbage that is difficult to clean out.
There is an option in deskpro to completely disable registration, but this is not a solution.

Imho what is needed is an option to stop creating users for each cc'ed email address to stop creating all the garbage.