Yahoo Sender Hub: set up the Complaint Feedback Loop (CFL)

What it means

When a Yahoo Mail or AOL user clicks Spam on one of your emails, Yahoo counts it as a complaint against you. Too many complaints and your emails start going to the spam folder, or get deferred with errors such as 421 [TSS04]. By default, you never see these complaints.

The Complaint Feedback Loop (CFL) fixes that. It is a free Yahoo program, managed from Yahoo Sender Hub (senders.yahooinc.com). Once your domain is enrolled, Yahoo sends you a short report for each complaint, in the standard ARF format (Abuse Reporting Format). You can then stop emailing that person.

Why it happens

Senders usually look for the CFL for one of these reasons:

• Yahoo or AOL is deferring or blocking your emails and you want to know why.
• Your email tool shows a rising complaint rate and you want the raw data.
• You run your own mail server, so no email provider handles complaints for you.
• You were enrolled in the old Yahoo feedback loop and need to move to Sender Hub.

Important: the CFL is domain-based and works only with DKIM. Yahoo identifies you by the domain in the d= tag of your DKIM signature. Emails without a valid DKIM signature for your domain are not covered.

How to check

1. Confirm DKIM first. On the Delivmail home page (/), copy your unique address and send it a normal email from the tool or server that sends to Yahoo. In the report, check that DKIM passes and note the signing domain (d=). If it shows your email provider's domain instead of yours, see authenticate your domain in your email tool.
2. Check DMARC. Yahoo requires SPF, DKIM and a DMARC record from bulk senders. Use the domain scanner to read your DMARC and DKIM records.
3. Check the headers. In a message received at a Yahoo address, open "View raw message" and look for dkim=pass header.d=yourdomain.com in Authentication-Results.

How to fix it

1. Make sure your emails are signed with your own domain

Turn on DKIM signing with your domain in your email platform, or in your own server (OpenDKIM, Rspamd...). The d= value should be yourdomain.com or one of its subdomains. If several tools send for you, each should sign with your domain so all streams are covered.

2. Create your Sender Hub profile and add your domain

Yahoo's CFL page lists three steps: create your sender profile, add and verify your domain, then enroll your domain. Sign in to Sender Hub with a Yahoo account, add the DKIM domain, and complete the ownership verification Sender Hub asks for (follow the exact instructions shown, as the method may change).

3. Enroll the domain in the Complaint Feedback Loop

Once the domain is verified, enroll it in the CFL and give the address that should receive the reports. Use a dedicated mailbox, for example fbl@yourdomain.com, that is read by a person or processed automatically. Make sure that mailbox accepts mail from Yahoo and does not filter ARF messages as spam.

4. Use the reports to remove complainers

Each report contains a copy of the email that was marked as spam. The recipient address may be hidden, so it helps to put your own subscriber ID in a header that is covered by your DKIM signature, or in the Message-ID. Then:

• Unsubscribe every complainer automatically, for all marketing streams.
• Look for patterns: one campaign, one list source, one type of email.
• Make unsubscribing easy with a one-click List-Unsubscribe header, so people unsubscribe instead of clicking Spam.

5. Watch your complaint rate

Yahoo's sender requirements ask bulk senders to keep the spam complaint rate below 0.3%, and lower is better. Sender Hub also shows aggregate data for verified domains. If the rate is high, read how to lower your spam complaint rate.

If you use an email service provider (Mailchimp, SendGrid, Brevo...), it may already receive Yahoo complaints through its own enrollment and suppress complainers for you. Your own enrollment still gives you direct visibility.

Check that it is fixed

Send a new Delivmail test and confirm that DKIM passes with your own domain. Then send an email to a Yahoo test mailbox you own and mark it as spam: a report should reach your feedback address, usually within a short time (delays happen). If nothing arrives, check that the email was DKIM-signed with the enrolled domain and that your feedback mailbox did not reject or filter the report. Fewer complaints help your reputation, but no setup guarantees inbox placement.