What are Precedence: bulk and Auto-Submitted headers?
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Picture this: someone sets up an out-of-office reply, and your newsletter fires back an automated response to that. Then their autoresponder replies again. Then yours does. You've just created an infinite loop that floods inboxes and burns your sending reputation. Two email headers exist specifically to prevent that from happening.
Precedence: bulk is an older header that tells receiving systems "this message is mass mail, not a personal note." You'll see a few variations in the wild:
- Precedence: bulk signals mass mailing (newsletters, campaigns)
- Precedence: list signals mailing list traffic
- Precedence: junk signals low-priority automated messages
It was originally the main tool for stopping autoresponders from replying to bulk mail. Today it's largely informational. Many systems still read it, but it doesn't carry the weight it once did.
Auto-Submitted is the more modern, more reliable solution (defined in RFC 3834). It tells the receiving server exactly what kind of automated message this is:
- Auto-Submitted: auto-generated covers system-generated messages like notifications or digests
- Auto-Submitted: auto-replied covers automatic responses like out-of-office messages
- Auto-Submitted: no (or no header at all) means a human wrote this
And the rule most autoresponders follow is simple: don't reply to anything with an Auto-Submitted value other than "no." That's what breaks the loop.
On the deliverability side, these headers don't directly move your email into the inbox or spam folder. But they do help receiving systems categorize your message correctly and handle it appropriately. Mislabeling automated mail as human-sent mail (or not labeling it at all) can look suspicious to filters, especially if your sending patterns are anything but personal.
If you're using an ESP like Postmark or Mailgun for transactional mail, they'll set these headers for you behind the scenes. If you're building your own sending infrastructure, include them. It's a small thing that signals you understand how the mail ecosystem is supposed to work, and systems do notice.
Not sure whether your email headers are set up correctly? Our free Email Header Analyzer can show you exactly what's being sent and whether anything looks off.
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