Feedback Loops (FBL) — Setup + Wire in AcelleMail

What FBL does for you#

When a recipient on a major ISP (Microsoft, Yahoo, AOL, Comcast) clicks "Mark as Spam," the ISP sends a feedback message to you describing the complaint. AcelleMail's Feedback Loop handler:

1. Receives + parses these messages from a dedicated address (e.g. [email protected])
2. Identifies the complaining subscriber + the original campaign
3. Auto-unsubscribes them (prevents future sends)
4. Updates the campaign's complaint rate stat
5. (Optional) Webhook out to your CRM / Slack

Without FBL setup, you don't see these signals. Complaints pile up silently until your IP reputation drops.

Setup overview#

[ISP side]                          [AcelleMail side]
1. Sign up for each ISP's FBL program
   → ISP needs an address to send to
2. Set up a `feedback@yourdomain` mailbox
                                     3. Configure FBL handler in sending server
                                     4. Test + verify

Phase 1: Sign up at each ISP#

Microsoft (JMRP)#

URL: https://sendersupport.olc.protection.outlook.com/pm/junkmail.aspx

Provide:

• Each sending IP / IP range
• Your contact + verification address (e.g. [email protected])
• Microsoft email account (free)

Approval: 24-48 hours.

Yahoo#

URL: https://senders.yahooinc.com/

Sign up for the Yahoo Feedback Loop service. Provides per-IP complaint forwarding to your verification address.

AOL / Verizon#

URL: https://postmaster.aol.com/

Similar process. Free.

Comcast / Xfinity#

URL: https://postmaster.comcast.net/

Form-based application.

Apple iCloud / Yahoo Postmaster#

iCloud doesn't have a public FBL program currently. The signals come via:

• Bounce log patterns (5.7.x codes for spam-policy blocks)
• iCloud's "Mail Privacy Protection" data via aggregate analytics

For iCloud, FBL isn't a setup task — accept that aggregate-level signals are all you get.

Phase 2: Set up the receiving mailbox#

Create a regular mailbox at [email protected] (any name; convention is feedback@). This is where ISP-generated FBL messages arrive.

The mailbox needs:

• IMAP or POP3 access (so AcelleMail can read it)
• Always-accessible (don't delete messages immediately — AcelleMail polls and acts)

Configure at your usual mail host (Google Workspace, Microsoft 365, Mailtrap, anywhere with IMAP).

Phase 3: Configure AcelleMail's FBL handler#

Open the sending-server detail#

In AcelleMail's sidebar, click Sending → Sending servers. The list shows every server connected to this account with its status chip, sending limit, and last activity:

Click into the row you want to configure. The detail page surfaces Connection settings (host / credentials), Configuration (server name, default from, sending limit, bounce + FBL handler), and the Test connection / Send test email buttons in the toolbar:

In the server detail's Configuration section (visible in the full-page server detail above), find the Feedback loop handler dropdown. The handlers themselves are managed as a reusable list at Admin → Sending → Feedback loop handlers:

Each handler is a named IMAP mailbox config — reusable across multiple sending servers. Define once, attach where needed. Click + New feedback loop handler to add a fresh one, OR edit the Default FBL Handler to point at your [email protected] IMAP credentials.

Back in the sending-server's Configuration field, the FBL handler dropdown lets you pick:

• None — FBL processing disabled (default)
• IMAP — AcelleMail polls an IMAP mailbox, parses FBL messages, processes them
• POP3 — Same via POP3 protocol

Pick IMAP (most modern). The expanded form asks for:

IMAP server:    imap.gmail.com (or your provider)
Port:           993 (TLS)
Username:       [email protected]
Password:       app-specific password
Poll interval:  5 minutes

Save. AcelleMail starts polling the mailbox.

Phase 4: Verify it's working#

Send yourself a test campaign. On a Microsoft / Yahoo account you control, click "Mark as Spam."

Wait 24-48 hours (FBL has delay). Then check:

1. The feedback message arrived in [email protected]
2. AcelleMail polled it (check the server's FBL processing log)
3. Your test address is now marked unsubscribed in the original list
4. Campaign feedback log shows the complaint:

If steps 1-2 work but 3-4 don't: check AcelleMail's FBL parser is recognizing the ISP's specific FBL format. Some ISPs use ARF (Abuse Reporting Format); others have custom headers.

Common FBL signals + actions#

Common UI signals + fixes#

Message-ID: <...>
Feedback-Type: abuse
User-Agent: ARF/1.0
Reported-Domain: ...
Original-Mail-From: ...
Original-Rcpt-To: ...
Source-IP: ...
Reported-URI: ...

Server A:  [email protected]
Server B:  [email protected]

# Daily cron — disable any server with complaint rate >0.3% yesterday
for server in $SERVER_UIDS; do
  cr=$(curl -sH "Authorization: Bearer $TOKEN" \
    "https://acellemail.com/api/v1/admin/sending-servers/$server/stats?day=yesterday" \
    | jq '.complaint_rate')
  if (( $(echo "$cr > 0.003" | bc -l) )); then
    # Disable + alert
    curl -X POST -H "Authorization: Bearer $TOKEN" \
      -d "{\"server_uid\": \"$server\"}" \
      "https://acellemail.com/api/v1/admin/sending-servers/disable"
    notify_slack "Server $server auto-disabled — complaint rate $cr"
  fi
done

curl -sH "Authorization: Bearer $TOKEN" \
  "https://acellemail.com/api/v1/admin/suppression?format=csv" \
  > suppression-snapshot-$(date +%Y%m%d).csv

Related articles#

• Sender reputation monitoring
• Microsoft SNDS walkthrough
• Email list hygiene
• Deliverability incident runbook