From osTicket Wiki

Email Settings

osTicket allows you to setup unlimited number of email addresses to handle all your company's mail accounts and email communication. Incoming emails are converted to support tickets allowing you to easily manage, organize and archive all emailed support requests in one place.

Email Templates

osTicket ships with generic email templates used for auto-responses, alerts, notices and replies. Refer to Email Templates Guide for details on how to customize or add new templates.

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.

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.

Outgoing Emails

By default osTicket uses native PHP Mail function to send outgoing emails. However, this can be problematic to spam filters depending on your php.ini mail settings. It is highly recommended that you use SMTP instead.

Each of the email accounts can have it's own SMTP. You can also setup a default SMTP system wide. See Settings tab in admin panel.