JIRA Service Desk will only create a new ticket , for newer email send after the incoming mail is configured . However , when there's a case user need UNREAD email previously before the incoming mail is configured . The email by default will be ignored and issue won't be created.
Always back up your data before performing any modification to the database. If possible, try your modifications on a test server.
Run below query :-
Take note on the result , get the email address
4. Get the starting date you would like to create issue from the mail inbox . The database use EPOCH date , so you may need to convert the date . Go to [http://www.epochconverter.com/] for the converter. Get the Timestamp in milliseconds result.
5. Update the PULL_FROM_DATE :-
Change the date and email address value.
6. Then restart JIRA .
Run the testing at Test Environment before performing at Production Environment