Mail Routing for Email to Case Premium
You are using Email to Case Premium and need to set up mail routing into Salesforce.
Email to Case Premium requires creating a routing address as part of the initial setup for the application. This routing address is tied to the Email Service packaged within Email to Case Premium.
To invoke the inbound features of Email to Case Premium (such as Auto-Add New Contacts, Forward to Case, Case Comment creation, and more), email messages coming into Salesforce must be directed to that routing address.
If your organization already provides addresses for customers to send to (such as firstname.lastname@example.org), you will need to work with your IT Team or Email Administrator to ensure email messages sent to these addresses are directed to the Email to Case Premium routing address configured in your Salesforce Org.
Below are a couple of knowledge articles to provide to your IT Team / Email Administrator for setting up mail routing from Office 365 and G-Suite:
Note: Existing routing addresses configured under Salesforce's Email-to-Case feature cannot be used with Email to Case Premium.