How to Create Email to Case Integration in Salesforce?
Email to Case is Standard Salesforce feature that allows case to be created from email. We will be looking into the details of On Demand Email to Case.
1.Go to Setup-Search for Case and Select Email-to Case..
2.Click ‘Edit’ Button..
3. Enable’ Email-to-Case’ and ‘On-Demand Service’..

4. Click ‘Save’ button..
5. Click ‘New’ button in Routing addresses. .

6.Enter Routing name and Email address. If you want to create task from Email, check Create Task from Email checkbox and select the task status. Select Case origin and Case status.

7. Click ‘Save’ Button. .
8. Click ‘Ok’ button to receive Verification email. .
9. Verify the routing address by clicking the link in the verification email.
10.Create Test Email with Subject and Body.Send email to ‘Email Services Address’.

11. Check it in your Salesforce organization whether case is created in Case object. Verify that Email Subject is properly populated in Case Subject and Email body gets populated in Case Description.
Conclusion:
Email to Case Automates the conversion of Emails to Cases without any Email-to-Case agent installation. Whenever customers send messages to email addresses which you specify, Salesforce creates cases and auto-populates case fields. It doesn’t accept the cases which have attachments more than 25 MB size.