Ok, that complicates things a little bit, to inspire you below an outline of what happens underwater:
The Render Email Content returns information about the generated messages in MetaData (or JSON). In MetaData a ‘document’ is created for every message. The MetaData contains a property called “_vger_prop_folder” which refers to the content of the message in Connect’s File Store. The MetaData also contains information like: to, from, cc, subject etc.
Our Sendgrid (and Mailjet) plugin iterates over the documents in the MetaData and fetches the respective content by calling the REST API of the OL Connect Server. Subsequently the plugin constructs the message following the SendGrid API and submits the data to the SendGrid API.
You could use “_vger_prop_folder” in the File Store - Download File tasks to fetch the content in zip format. Alternatively interact with the OL Connect Server API from a Run Script (not sure if you are up for that). In that case you could download the html body in a single request by concatenating “_vger_prop_folder” and “_vger_prop_body”.
Hope this helps,