First, login to the admin section of your SupportSuite installation. Now insert a new mail parser rule by selecting Mail Parser » Manage Rules » Insert New Parser Rule in the left navigation menu. Now configure the parsing rule as follows:

Rule Title: Close Ticket via Email
Stop processing rules: No
Execution Order: 1

Now add three criteria (press the green plus icon to add more than one criteria).

Body » Contains » close this request
Plain-text Body » Contains » close this request
HTML Body » Contains » close this request

You can change ‘close this request’ to whatever you like, but keep in mind it should be something that isn’t likely to occur in a ticket response (i.e., ‘close’ would probably be too generic).

If you have more than one email queue and you only want this mail parser rule to apply to a specific queue, you can add a forth (optional) criteria:

Destination E-mail Address: [mail queue address, i.e., support@mycompany.com]

Now finish configuring this parser rule:

Select Match Any Criteria
Set Rule Type: Post Parse
Change Ticket Status: Closed

That’s it! Now press Insert and you’re done.