Darren, we haven't done this before, but there is definitely to do this.
Can you clarify how you currently track inbound emails? What CRM are you using?
Like many organizations, we use Salesforce's native email-to-case module for all lead, customer, and support inquiries. Each inbound email to tracked addresses create a new Salesforce Case.
Marketo's standard functionality only allows you to read/write Lead/Contact objects and read Account object. If you wanted to send out auto-responders based on email subject or body criteria, you could do one of the following:
-
Link Marketo to your Salesforce Case object
-
Create a series of workflows that updated the related Contact or Lead record with the person's latest email
From there, you would create a Marketo campaign that looks at the field you've linked with inbound emails and trigger canned responses based off the criteria you want to specify.
One thing I'd caution, though, is to err on the strict side when it comes to criteria. Your organization might look very silly if you sent out instructions on how to opt-out when the lead was actually asking for something else. Here is a recent example of how Bank of America failed:
http://gizmodo.com/bank-of-americas-twitter-account-is-one-really-really-713634226Hope this helps.