You can certainly launch a process based on reading an email, or any other event that PAM can process including SNMP, etc. There are also command line (CLI) and web services (SOAP, REST 4.x). I also recently saw an example of launching a process using web services called from Javascript in a UI. I've used email but parsing parameters for inputs can sometimes prove challenging unless there are some strict rules for formatting, so having a user manually send a email may prove unreliable. If you must use email, then consider automating the send using a well defined format with minimal variables.
You can also post such questions to the CA sponsored forum:
https://communities.ca.com/web/ca-process-automation-global-user-community/