The opt-in permissions drive the email marketing cycle (shown below). If you remember, GDPR means that you can only send marketing to those people who have given consent/opt-ins. These opt-ins need to be specific rather than just an overall marketing opt-in. Here are examples of three different opt-ins :  product updates by email; event invites by email; event invites by SMS.

The opt-ins determine which people are added and removed from the Pardot Lists or your marketing automation solution. The challenge is completing the cycle, since the unsubscribes and resubscribes received in Pardot need to be reflected back as updates to the opt-ins in Salesforce.

Salesforce Leads and Contacts control which records are added to Pardot Marketing Lists. Prospects can be added to Pardot but should NOT be added directly to Pardot Lists. The prospect is synced with Salesforce and, based on privacy permissions, it is then automatically added to Pardot Marketing Lists.

Each Communication Rule is mapped to one or more Pardot Marketing Lists. So, when a person is subscribed to a Communication Rule in Salesforce, they are automatically added to the mapped Pardot Marketing Lists.

When a person unsubscribes in Salesforce from a Communication Rule, they are automatically removed from the mapped Pardot Marketing Lists. If a person unsubscribes from a Pardot Marketing List then the privacy permissions for the related Communications Rule will be updated in Salesforce.

When a new prospect is created in Pardot from a lead form  - which has a consent/subscribe  -  it will be automatically added to Salesforce and the privacy permissions will also be added. It will not be added to a Marketing List.

The Communication Rules each have an auto-generated six digit code. The Privacy Sources each have an auto-generated six digit code. You can see the allocated codes in the Data Privacy Admin tab under Integration Codes.

Lead and contact records have a new custom field “Communication Rules” which is automatically updated with all the codes of the Communication Rules that the person is allowed to be contacted with.

Salesforce Tasks are created by Pardot to drive changes back into Salesforce. The managed package has an Apex trigger that processes Salesforce Tasks for contacts and leads where the subject and description are in a special DPM format. Any third party app can also add a Salesforce Task in the special DPM format to add permission records or unsubscribe.

2. Create two automation rules for every Marketing List. One to add, and one to remove prospects to that Marketing List based on code for the Communication Rules that are contained in the “Communication Rules” field.

3. Create a Salesforce Task to communicate from Pardot to Salesforce. An Apex trigger will process the Salesforce Task based on the subject and comment text. The formatting of the Salesforce Tasks is in next section. These are the Salesforce Tasks you may need to set up:

a. Subscribe to a list — set up using a Pardot Automation Rule.

b. Unsubscribe from a list — set up using a Pardot Automation Rule.

c. Add a prospect from a Pardot form (simple) — use Pardot Form completion action.

d. Add a prospect from a Pardot form (dependent on field values) — use Pardot form handlers. Here is the help explaining how to do this https://help.salesforce.com/articleView?id=Using-Form-Field-Based-Completion-Actions&language=en_US&type=1.

To use Salesforce tasks see this article