For those working in a Salesforce Org with Enterprise Edition or higher, Email to Case Premium provides an automated mechanism for generating the Email Service as part of the setup process.

However, users on Professional Edition do not have access to this feature. Setup on Professional Edition requires the manual generation of the Email Service and Routing Address through the Salesforce Setup menu. Please follow the steps below:

1. Navigate to Setup | Custom Code | Email Services, and click New Email Service.
2. Specify "Email to Case Premium" as the Name, and "ProcessMessage" as the Apex Class.
3. Enable the "Active" and "Error Routing" checkboxes.
4. Specify an administrator's address in the "Route Error Emails to This Email Address" setting.
5. Click Save.
6. Under the "Email Addresses" section, click "New Email Address"
7. Specify "Email_to_Case_Premium" in the Name and Email Address fields.
8. Ensure the "Active" checkbox is enabled, and specify a Context User.
9. Ensure the "Accept Email From" box is blank, and click Save.
10. Lastly, work with your Email Administrator to forward emails sent to your organization's addresses (such as techsupport@companyxyz.com) to the newly created Email to Case Premium routing address.