De acordo com a documentação oficial do osTicket, existem dois métodos para buscar e-mails: Piping de Email e Polling POP3 / IMAP. E ambos exigem configuração adicional, o que você está perdendo.
Routing Incoming Emails
Setting up your system to accept emails varies from system to system and depends on your personal preference. osTicket currently supports piping (aliases) and POP3/IMAP polling methods for routing incoming emails. Tickets are routed to the department and assigned a default priority associated with the email.
To enable incoming email fetching, in the Admin panel go to Settings and Email, and check the box for Email Fetching to enable it. It is disabled by default.
Email Piping
Piping method allows for real-time email handling. Extra setup is required at mail server level to pipe the raw email message to osTicket pipe handler. Both remote and local piping are supported. See Email Piping Guide.
POP3/IMAP Polling
POP3/IMAP account polling method is best suited for individuals with remote mail account(s) and/or with limited access to mail delivery settings. Each email address added to the system can have an account associated to it. See POP3/IMAP Setting Guide.