Okay yea that doesn't make much sense to me. Is helpdesk@ the email you are trying to configure in osTicket? If so, try clearing your cache/cookies/sessions, setting your Agent Session Timeout in the system to 0 and retest. It seems like it's dropping your authenticated session somehow which is baffling to me if you are running v1.17.2 and the patches I linked above.
Cheers.