Gravater accounts with mix case emails causes a break in the sense that their avatar is not picked from Gravater. This has been tested for both LDAP and internal users. Here is a summarry of the results:

1. User: sultan email: sultan.jira@gmail.com OK
2. User: sultan email: Sultan.Jira@gmail.com NOT OK

Workaround
User details in the internal directory can be edited to change the email case. This will not break the email notifications since mails are case insensitive.

In the case of LDAP users, there are two scenarios:

1. If the LDAP permission is read/write, then we can as well change the email address from JIRA
2. For the case of read-only permissions, the change has to be done in LDAP