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Error 'Undeliverable: Case is Rejected' when a Mail Delivery system sends multiple emails

Julkaisupäivä: May 2, 2026
Kuvaus

This article describes a scenario where an Email-to-Case (E2C) auto-response loop causes repeated "Undeliverable" and "Case is Rejected" error messages between a mail delivery system and the Salesforce organization-wide email address.


Steps to Reproduce:

  1. An email is sent to the Email-to-Case (E2C) routing address and a case is created.
  2. An auto-response email is sent from the organization-wide email address to the contact.
  3. After 24 hours, the mail delivery system sends an undeliverable notice to the organization-wide email address: "A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: xyz@email.com (Undelivered): 554 5.4.7 [internal] exceeded max time without delivery"
  4. After another 24 hours, the mail delivery system sends a second message to the organization-wide email: "Undeliverable: Case 5000a00000***** is Rejected."
Ratkaisu

This error occurs because Salesforce's Email-to-Case (E2C) feature has entered an auto-response loop between the mail delivery system and the org's organization-wide email address. The original contact email address was invalid, which triggered an "Undeliverable" bounce notice. Salesforce read that bounce as a reply to the case, which triggered another auto-response — creating a continuous loop.

Option 1: Temporarily Stop Forwarding Emails

Temporarily stop forwarding emails from your mail server to the Email-to-Case (E2C) service address. This breaks the loop immediately while you investigate the root cause.

Option 2: Set Up a Mail Server Filter

Configure a filter on your mail server to check for keywords such as "Error" and "Undeliverable" in incoming messages and exclude them from being forwarded to the E2C routing address. This is the preferred long-term solution.
Note: Both options are configured on your organization's own mail server — not within Salesforce directly.

Knowledge-artikkelin numero

000384020

 
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Salesforce Help | Article