Searching for a user with particular email address formulations in the Customers page by email doesn't return the user

Issue Summary

On the Customers page (/jira/servicedesk/projects/<ProjectKey>/customers), searching for certain customers who have a different name to their email address, by the email address exactly, does not return the user as expected.

Steps to Reproduce

1. On the Customers page (<instance hostname>/jira/servicedesk/projects/<ProjectKey>/customers) add mr.anderson@example.comdonotuse as a customer.
2. go to the user management UI -> Jira Service Desk Customers (e.g. http://<instance>.atlassian.net/admin/jira-service-desk/portal-only-customers), and click "Edit full name" to set their name to something that doesn't look like their email address, like "Mr Anderson".
3. Try the search on the Customers page with the string mr.anderson@example.comdonotuse.
4. Try the same search bar with "Mr Anderson" or any substring thereof.

Expected Results

The user is returned when searching by either name or email address.

Actual Results

The user is returned when searching by name, but not by email address.

Workaround

As a partial workaround, either:

• Search for the user by name, rather than email address, or
• Search for the user by email address on the Jira settings -> User management -> Jira Service Desk customers page.