Limit who can submit a support ticket to your site?

Limit who can submit a support ticket to your site?

Does anyone have a use case for needing to limit who can submit tickets via your help portal? Some of our customers want to have end-users view our knowledge base articles and see tickets their IT groups have submitted but they do not want end-users to submit tickets via the portal. I don't think zoho desk has a way to limit who can submit tickets or a way to have different user groups within your help portal.

Is this a common use case for anyone?