Sorry for the delay - Mailjet is a mail transfer agent system, a lot like Amazon SES, but much simpler. What I want to do is avoid using PHP mail to send notifications from the system, and route all outgoing mail through to the third party system. This will give me better logging and tracking of responses sent for things like password resets.
Typically, using MailJet would replace the PHP mail, and allow me to enter an API key pair to the configuration, then the OSTicket software would route all outgoing mail to Mailjet.
So it's not like a collaborator - it's a replacement for PHP mail.