Lettermint
Send with

Listmonk

Use Lettermint to send your Listmonk newsletters through SMTP and report bounces and spam complaints to Listmonk.

Before you start

You need a running Listmonk instance, a verified sending domain, and a Lettermint project with SMTP enabled.

Use a broadcast route for newsletters. Set it as the project's default outbound route before you send a campaign.

Connect SMTP

In Listmonk, open Settings, then SMTP. Enable SMTP and select the Lettermint preset.

Set the username to lettermint and the password to your Lettermint Project API token. Save the settings and use Test connection to check them. If your Listmonk version has no preset, use the SMTP connection settings.

Set your Listmonk sender address to an address on your verified domain.

Connect bounce webhooks

Create a webhook on the Lettermint broadcast route. Use your Listmonk address with this path:

Code
https://listmonk.example.com/webhooks/service/lettermint

Select these events:

  • message.hard_bounced
  • message.soft_bounced
  • message.spam_complaint

In Listmonk, open Settings, then Bounces. Enable bounce processing, bounce webhooks, and Lettermint. Copy the Lettermint webhook's signing secret into the Lettermint Webhook Secret field and save the settings. Include the whsec_ prefix.

See Listmonk bounce processing for subscriber actions after a bounce or complaint.

Include the campaign ID

If Listmonk records bounces without a campaign ID, add this custom header to your Listmonk campaign:

JSONCode
[
  {"X-LM-Metadata-X-Listmonk-Campaign": "{{ .Campaign.UUID }}"}
]

Listmonk replaces the template with the campaign UUID. Lettermint adds it to data.metadata["X-Listmonk-Campaign"] in the webhook. This works with Listmonk versions that read the campaign ID only from metadata.

Listmonk versions that read webhook headers can use the standard X-Listmonk-Campaign header instead. Adding the metadata header applies to new messages only.

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