SD: Block public signup

[Thomas Deiler]

Requirement

We use SD (3.16.3) for internal employees, only. All "customers" already have a login to Jira. So they don't need to sign up to raise tickets. Additionally we allow out customers to send emails that are converted to tickets. (public signup up and email request are bound together)

Problem

With the "sign up" link on the portal, the users are irritated. Some create a new account. We tried to disable the /servicedesk/customer/portal/1/user/signup page by following this article: https://confluence.atlassian.com/kb/how-to-block-access-to-a-specific-url-at-tomcat-966668691.html We also tried to block the page within nginx with a 

location /servicedesk/customer/portal/1/user/signup {
  return 444;
}

command. Both were not successful. Only when reloading the signup page it is blocked. Also when continuing with the sign up an error is shown:

We were unable to submit your request. Please refresh the page and try again. Note that this will clear your request details.

If you have already tried again, contact your Jira Administrator.

We assume, that SD as a plugin/application catches the path requests before either nginx or tomcat can block them.

I already had a look at https://jira.atlassian.com but could not find any suggestion similar to our requirement.

Does anybody know a solution? Or is raising a new suggestion the only way?

[Thomas Deiler]

As the amount of answers is overwhelming, I created a new suggestion. Feel free to vote.