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Feedback loops (FBLs) are programs that let mailbox providers report spam complaints back to senders. Keeping your complaint rate low is essential for inbox placement.

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What is a feedback loop

When a recipient clicks “Report spam” or “Junk” in their mail client, the mailbox provider can forward a copy of that message back to the sender through a feedback loop. The report is usually sent in Abuse Reporting Format (ARF). This lets you identify which campaigns, lists, or content generated complaints so you can fix the root cause.
Complaint data is only useful if you act on it immediately. Remove complainers from your lists right away.

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Major feedback loop programs

Not all providers offer traditional feedback loops, and the enrollment rules differ.

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Microsoft JMRP and SNDS

Microsoft offers the Junk Mail Reporting Program (JMRP). Complaint reports come through the same portal as Smart Network Data Services (SNDS). You must sign up for SNDS and register your IPs to receive JMRP data.

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Yahoo Complaint Feedback Loop

Yahoo provides a Complaint Feedback Loop that is DKIM-based. You must sign up with Yahoo, prove domain ownership, and have valid DKIM signing in place. Complaints are returned in ARF format.

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Gmail

Gmail does not offer a traditional feedback loop. Instead, senders should:
  • Add a Feedback-ID header to campaigns for troubleshooting.
  • Use Google Postmaster Tools to monitor domain reputation and spam rate.
  • Keep the spam rate below 0.1% and never reach 0.3%.

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Complaint rate thresholds

Complaint rates vary by industry, but the safe targets are the same across major receivers: Sustained rates above these limits often lead to temporary throttling, spam folder placement, or blocks.

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How mySMTP handles complaints

Complaints must be removed from your mailing lists immediately. This protects both your reputation and the shared infrastructure. If you are unsure how complaint data is shared for your account, contact support@mysmtp.com.
Run the Sender Readiness Checklist in the mySMTP Deliverability Toolbox to audit your list hygiene and sending practices before you scale volume.