Workflow to react on e-mail content

Hello,
is it possible to make a workflow that would read an incoming email body and react according to it’s content?

The grand plan is folloing, i have a set of leads wich i call, after the call i log a call, and send an e-mail (it happens automatically after changing the status of the lead). After this, there are 2 possiblities, eighter the person signs up on the website and i get an email with ticker-symbol of the lead in the body or, they don’t sign up and i would like the system to send an automated reminder.

As to recognize the registration i can,

  1. read the mail and look for the ticker_symbol
  2. treat any incoming email with leads address and sybject signup as registration (alltho they can signup with another email)

What would be the easiest aproach to this?

Thank you.