Bounce processing

Enable bounce processing in Settings -> Bounces. POP3 bounce scanning and APIs only become available once the setting is enabled.

POP3 bounce mailbox

Configure the bounce mailbox in Settings -> Bounces. Either the "From" e-mail that is set on a campaign (or in settings) should have a POP3 mailbox behind it to receive bounce e-mails, or you should configure a dedicated POP3 mailbox and add that address as the Return-Path (envelope sender) header in Settings -> SMTP -> Custom headers box. For example:

[
    {"Return-Path": "your-bounce-inbox@site.com"}
]

Some mail servers may also return the bounce to the Reply-To address, which can also be added to the header settings.

Webhook API

The bounce webhook API can be used to record bounce events with custom scripting. This could be by reading a mailbox, a database, or mail server logs.

Method	Endpoint	Description
POST	/webhooks/bounce	Record a bounce event.

Name	Type	Required	Description
subscriber_uuid	string		The UUID of the subscriber. Either this or email is required.
email	string		The e-mail of the subscriber. Either this or subscriber_uuid is required.
campaign_uuid	string		UUID of the campaign for which the bounce happened.
source	string	Yes	A string indicating the source, eg: api, my_script etc.
type	string	Yes	hard or soft bounce. Currently, this has no effect on how the bounce is treated.
meta	string		An optional escaped JSON string with arbitrary metadata about the bounce event.

curl -u 'api_username:access_token' -X POST 'http://localhost:9000/webhooks/bounce' \
    -H "Content-Type: application/json" \
    --data '{"email": "user1@mail.com", "campaign_uuid": "9f86b50d-5711-41c8-ab03-bc91c43d711b", "source": "api", "type": "hard", "meta": "{\"additional\": \"info\"}}'

External webhooks

listmonk supports receiving bounce webhook events from the following SMTP providers.

Endpoint	Description	More info
https://listmonk.yoursite.com/webhooks/service/ses	Amazon (AWS) SES	See below
https://listmonk.yoursite.com/webhooks/service/sendgrid	Sendgrid / Twilio Signed event webhook	More info
https://listmonk.yoursite.com/webhooks/service/postmark	Postmark webhook	More info
https://listmonk.yoursite.com/webhooks/service/forwardemail	Forward Email webhook	More info

Amazon Simple Email Service (SES)

If using SES as your SMTP provider, automatic bounce processing is the recommended way to maintain your sender reputation. The settings below are based on Amazon's recommendations. Please note that your sending domain must be verified in SES before proceeding.

1. In listmonk settings, go to the "Bounces" tab and configure the following:
   • Enable bounce processing: Enabled
     • Soft:
       • Bounce count: 2
       • Action: None
     • Hard:
       • Bounce count: 1
       • Action: Blocklist
     • Complaint:
       • Bounce count: 1
       • Action: Blocklist
   • Enable bounce webhooks: Enabled
   • Enable SES: Enabled
2. In the AWS console, go to Simple Notification Service and create a new topic with the following settings:
   • Type: Standard
   • Name: ses-bounces (or any other name)
3. Create a new subscription to that topic with the following settings:
   • Protocol: HTTPS
   • Endpoint: https://listmonk.yoursite.com/webhooks/service/ses
   • Enable raw message delivery: Disabled (unchecked)
4. SES will then make a request to your listmonk instance to confirm the subscription. After a page refresh, the subscription should have a status of "Confirmed". If not, your endpoint may be incorrect or not publicly accessible.
5. In the AWS console, go to Simple Email Service and click "Identities" in the left sidebar.
6. Click your domain and go to the "Notifications" tab.
7. Next to "Feedback notifications", click "Edit".
8. For both "Bounce feedback" and "Complaint feedback", use the following settings:
   • SNS topic: ses-bounces (or whatever you named it)
   • Include original email headers: Enabled (checked)
9. Repeat steps 6-8 for any Email address identities you send from using listmonk
10. Bounce processing should now be working. You can test it with SES simulator addresses. Add them as subscribers, send them campaign previews, and ensure that the appropriate action was taken after the configured bounce count was reached.
    • Soft bounce: ooto@simulator.amazonses.com
    • Hard bounce: bounce@simulator.amazonses.com
    • Complaint: complaint@simulator.amazonses.com
11. You can optionally disable email feedback forwarding.

Exporting bounces

Bounces can be exported via the JSON API:

curl -u 'username:passsword' 'http://localhost:9000/api/bounces'

Or by querying the database directly:

SELECT bounces.created_at,
    bounces.subscriber_id,
    subscribers.uuid AS subscriber_uuid,
    subscribers.email AS email
FROM bounces
LEFT JOIN subscribers ON (subscribers.id = bounces.subscriber_id)
ORDER BY bounces.created_at DESC LIMIT 1000;