Pass Email content as a field to Salesforce

We are wanting to be able to pass the content (body) of an email as a field from Marketo to Salesforce (then on to Outreach to eventually send the email).

Basically how we want it to work is if a lead does a specific activity, we want a field to populate with a specific message.  Then the lead and all the details will be passed to Salesforce where the email content will be stored in a field there. 

Is there a way we can store the actually wording of an email somewhere in Marketo, and pull it into the flow of a smart campaign?