Summary

It is now possible add JIRA Service Desk customers as assignee and watchers via email.

Steps to Replicate

1. Go to JIRA incoming mail handler page and edit the mail handler of an existing project. Tick 'CC Assignee' and 'CC Watchers'.
2. Create a Service Desk customer.
3. Send an email to create a ticket in the mail handler edited on step. Make sure to include the customer in step 2 to the CC field.

Expected Results

Service Desk customers should never be added as assignees or watchers.

Current Results

You can add customers to assignee and watchers via email using the CC field.