Email addresses in the 'to' or 'cc' field are added as request participants and to the project customer list when public sign up is disabled.

Summary

When sending an email to an inbox for a JSD project, the additional email addresses on 'cc' or 'to', are added to the customer project list, an account gets created in the user management and they are added to the issue as a request participant even though public sign up is disabled.

Please not that this behaviour only happens when the email is being sent by a project administrator.

Environment

JIRA Service Desk Cloud

Steps to Reproduce

1. Disable public sign up in your JSD project. Both in the general JIRA Service Desk configuration and the project customer permissions. 
2. Send an email to your project inbox

Expected Results

No new customer account gets created, added to the project list or added as request participant to the newly created ticket

Actual Results

A new customer account gets created on the email in the 'to' or 'cc' field will be created and added to the customer project list and also included as a request participant in the newly created ticket.