The email requests handler is unable to Active Dicrectory ldap uses with mix usernames as participants.

Steps to reproduce.

1. create user via ldap with username : TestUser
2. send an email and add the user in the cc to be created as participant

Expected Result

The user to be added as participant

Actual Result

The following error will be logged by the mail handler

17/Apr/18 8:28 AM	FAILURE	Sorry, but the following usernames could not be added as participant to this request: testuser	test@test.com	RE: test email 	Service Desk Mail Handler

Workaround

Change the username to lowercase.