Hi,
The source email will only be populated when the contact or lead is generated from a marketing email which contains a marketing form.
First of all, you need to use the Marketing application in Dynamics.
For example, I created a landing page marketing form which will create or update contacts/ leads.
It is inserted into a marketing page.
Insert the marketing page into a marketing email.
Send the email to a contact. The contact opened the form from the received email and submit a new contact’s info.
The new contact will be created then and the source email will be populated with the marketing email.
