Best Practices on Email Retention and Email Loops Prevention in Email-to-Case

When an error occurs during Email-to-Case processing, the Case or Inbound Email Message record is not created. The Case must be either created manually, or resubmitted through the saved email in the internal Routing Address inbox.
Implement the following best practices to prevent email loops and ensure reliable processing of Email-to-Case.

Retain Inbound Emails

When redirecting emails from the Routing Address internal inbox to the Email Services Address, retain the original received email in the inbox or save it in another folder or location. This provides a backup of all emails received and redirected to Salesforce, which is important for compliance purposes. If a processing error occurs, the saved email can be used to manually recreate or resubmit the Case.

Configure the Automated Case User Email Address

Do not use an Email-to-Case Routing Address as the email address for the Automated Case User. Using a Routing Address for this purpose can potentially cause an email loop situation, where error notification emails are themselves processed as new inbound cases. Instead, ensure that the Automated Case User email address belongs to a User who can monitor for errors. Another option is to assign an internal email alias that distributes to a group of internal Users, so multiple team members can monitor for and respond to processing failures.

Avoid Using Routing Addresses for Other Salesforce Functions

It is not recommended to use Email-to-Case routing addresses for other functionalities in Salesforce that send emails — such as queues, organization-wide addresses, and records (like Contacts or Leads). Using the routing address in multiple places increases the risk of email loops, where automated emails sent by Salesforce are re-processed as new Email-to-Case requests.