Skip to main content
Listmonk Listmonk is the one channel in the calendar that sends email. It connects the way self-hosted software usually does, with an address and a login rather than an OAuth app, so there is nothing to register and nothing to add to your .env file. You click Listmonk in Add Channel and type three values into the form that opens.
Publishing sends the campaign. She creates the campaign in Listmonk and immediately sets its status to running, in the same publish. No draft campaign is left behind for you to look over, and there is no second click on the Listmonk side. A post scheduled for Tuesday at nine means the email leaves at Tuesday at nine.

​
What she can post to Listmonk

You are writing an email, not a status. The editor is the HTML one, the subject line and the list live in the post settings, and the whole thing goes out as one regular campaign.

Character limit

300,000 characters in the composer, which is far past anything a newsletter needs.

Media

None uploaded. Files attached to the post are not sent to Listmonk, so images belong in the HTML body as links to somewhere they are already hosted.

Post types

One campaign to one list. Extra boxes added under the post are not sent, because this connector has no comment or thread call at all.

Analytics

None. Ten connectors report numbers back to her, and Listmonk is not one of them. Open rates stay in Listmonk where they are collected.
Two details about the body she builds. The Preview text becomes the hidden preheader of the email, the line most clients show next to the subject, padded so the rest of your HTML does not leak into that preview. Select Template offers a Default entry, and choosing it sends the campaign without a template id so Listmonk falls back to its own default. The campaign name in Listmonk is your subject line, slugified.
The LISTMONK_ environment variables are not this channel. LISTMONK_DOMAIN, LISTMONK_USER, LISTMONK_API_KEY, LISTMONK_LIST_ID and LISTMONK_WELCOME_TEMPLATE_ID appear in the Configuration Reference under newsletter providers, and they belong to a different subsystem: the product newsletter that subscribes new PostQueen users and sends them a welcome email. Setting them does nothing for this channel, and leaving them empty takes nothing away from it. The Listmonk channel needs no environment variables. Your instance address and login live with the channel, encrypted, and nowhere else.

​
Connect Listmonk

1

Create an API user in Listmonk

Open your Listmonk admin, go to Admin and then Users, and create a user of the API type. Listmonk shows you the token once, at creation, so copy it before you leave the page. That token is what you paste as the password further down.Give the user access to the parts of the API she calls: the settings endpoint she checks the login against, your lists and your templates for the two dropdowns, and campaigns for creating and starting the send.
2

Open Add Channel and pick Listmonk

In PostQueen, click Add Channel and select Listmonk. A modal titled Add Provider opens with three fields, and you stay inside PostQueen the whole time.
3

Fill in the three fields

Each label below is exactly what the modal shows you.
4

Press Connect

She calls /api/settings with those credentials as basic auth. The channel then takes its name from your Listmonk site name and its picture from your Listmonk logo, so a channel that appears with your newsletter branding is the sign it worked.
5

Write the campaign

Choose the Listmonk channel in the editor and fill in the settings. Subject is the email subject line, Preview is the preheader, Select List is the audience and Select Template is optional. Then write the email itself in the HTML editor.Publishing creates the campaign and starts it at once, so treat the schedule time in PostQueen as the send time.
The channel is in the left sidebar with its avatar and name. That is the whole confirmation: if it is in the list, she can post to it.

​
Troubleshooting

​
”Invalid credentials” when connecting

The call to /api/settings did not come back with a settings payload. Check the three fields in this order: the URL resolves and serves Listmonk, the API user is spelled the way Listmonk has it, and the token is the one from that user. A user without access to the settings endpoint fails here even though the name and token are right.

​
The list dropdown does not appear

Select List renders nothing when the call behind it comes back empty, which means an empty account or an API user without access rather than a broken editor. Create a list in Listmonk, or widen the user’s access, then reopen the post. Select Template is different: PostQueen always prepends a Default entry, so a successful call can never come back empty. An empty template dropdown means the call to Listmonk failed outright. Check the URL and the credentials.

​
The email went out the moment the post published

That is the connector working as built. Listmonk campaigns are created and set to running in one publish, so the PostQueen schedule is the send schedule. If you want a campaign sitting in Listmonk for review, build that one by hand in Listmonk.

​
Listmonk on localhost or a private address

The field accepts localhost, an IP address and a port, so the form lets you type it. The backend is stricter: requests resolving to loopback, private or link-local addresses are blocked before they leave. On a deployment where PostQueen and Listmonk share a trusted private network, set DISABLE_SSRF_PROTECTION=true, which is documented beside the setting in .env.example.