How to resolve Callout Exception: 403 - Forbidden Error with Marketing Cloud Connect
Something new happened I have not seen before so I thought I would share.
After installing Marketing Cloud Connect package and setting up Marketing Cloud with Salesforce (by following the usual procedure) I was getting a weird error when clicking on Email when trying to test connectivity in between Salesforce and Marketing Cloud.
If you ever come across this, the way to resolve this (in addition to the assigned correct User Role) you need to go to Account > Users > User Name > Edit permission > Email > Integration > Check the checkbox for allow for Salesforce CRM and salesforce Send > save it. Please see the image below.
I hope I managed to save you some time. :)