Stalwart Mail Server certificates.
One DNS setup. Easier renewals.

Why put Stalwart Mail Server behind this certificate workflow?

All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.

For a private Stalwart Mail Server deployment, maintaining public port-80 validation just for renewal can add routing work. A native DNS-01 client can avoid that listener but may need a supported DNS-provider integration and its credentials. SimpleACME is our preferred option when you want a permanent challenge delegation and one renewal workflow across different services.

Keep application access controls, backups and network policy in place. This guide adds an HTTPS endpoint to an existing service; it does not install Stalwart Mail Server, provision its database, or make an unauthenticated application safe to expose.

Configure Stalwart Mail Server step by step

1. Check the existing Stalwart Mail Server endpoint

   Keep Stalwart Mail Server installed using its upstream deployment instructions. The linked source includes an example listener or published HTTP endpoint on port 8080. Confirm your own private endpoint from the gateway host before copying the router. The port is a documented example, not a universal default for every version or installation.

2. Choose the HTTPS hostname

   Use a dedicated hostname such as stalwart-mail-server.example.com at the domain root. Make it resolve to your gateway for your clients, using private DNS if appropriate. Keep the application backend reachable only by the gateway and preserve the application’s authentication.

3. Prepare the domain and permanent CNAME

   Add the intended hostname in SimpleACME. A single-domain demo can prepare DNS before payment and cannot send TXT updates. Copy the exact _acme-challenge owner and assigned CNAME target from the domain card into your authoritative public DNS, then use Check CNAME.

4. Connect the certificate renewal client

   Activate the matching paid domain, then configure Traefik’s simpleacme certificate resolver using the subscriber Traefik guide. Preseed the ACME-DNS account file with that domain’s existing credentials. The public /register route is closed; the client must reuse its registration. Use staging first.

5. Align Stalwart Mail Server with the HTTPS origin

   Use stalwart-mail-server.example.com as the public origin for this Stalwart Mail Server deployment. If your installed version exposes a public/base URL, allowed-host, callback or trusted-proxy setting, configure it using the linked project instructions. Trust forwarded headers only from the actual gateway. The gateway fragment below does not change Stalwart Mail Server configuration or install the application.

6. Add the Stalwart Mail Server HTTPS router

   Merge the named router and service below into the file watched by your existing Traefik file provider. Replace the example hostname and documentation address 192.0.2.10 with the real hostname and private backend IP; use your actual published HTTP port. Keep existing routers and services.

7. Verify the complete client journey

   After staging succeeds, select the production certificate authority in your resolver. Open https://stalwart-mail-server.example.com/ from an authorized client and check hostname, certificate chain and expiry. Test Stalwart Mail Server login, uploads, WebSockets, API requests and callbacks that your deployment uses. This route covers HTTP traffic; SSH, SMTP, media, discovery and other transports require their own configuration.

8. Keep renewal and monitoring enabled

   Leave the challenge CNAME in place and keep Traefik running with persistent ACME storage and current paid domain access. Monitor DNS challenge activity in SimpleACME and the actual served certificate independently. A TXT change is an authorization event, not proof that Stalwart Mail Server renewed or installed a certificate.

Check the private Stalwart Mail Server backend

curl --head --connect-timeout 5 http://192.0.2.10:8080/

Run from the gateway network after replacing the documentation IP and port with your actual Stalwart Mail Server endpoint. Authentication responses and redirects can be expected; do not disable authentication to make a test return 200.

Stalwart Mail Server Traefik router example

# Merge these entries into the file watched by your existing Traefik file provider.
# Requires the simpleacme resolver and your pre-registered ACME-DNS account.
# Replace the hostname and 192.0.2.10 with your real hostname and private backend IP.
http:
  routers:
    stalwart-mail-server:
      rule: 'Host(`stalwart-mail-server.example.com`)'
      entryPoints: [websecure]
      service: stalwart-mail-server
      tls:
        certResolver: simpleacme
  services:
    stalwart-mail-server:
      loadBalancer:
        passHostHeader: true
        servers:
          - url: 'http://192.0.2.10:8080'

The fragment assumes a websecure entrypoint and a simpleacme resolver already configured by the subscriber Traefik guide. Merge entries into the watched dynamic file rather than overwriting other applications. Replace the sample hostname with the exact paid hostname; keep credentials and certificate storage private.

Verify the trusted HTTPS endpoint

curl --head --resolve stalwart-mail-server.example.com:443:192.0.2.20 https://stalwart-mail-server.example.com/

Replace the second documentation address with the gateway IP and use this after a trusted production certificate is installed. Staging certificates are intentionally untrusted. Do not hide trust or hostname errors when validating the production setup.

Compare ACME validation for Stalwart Mail Server

Our recommendation for Stalwart Mail Server: choose SimpleACME when private-service validation, fewer DNS credentials and a reusable gateway matter most. HTTP-01 remains a valid choice for an already-public responder; narrowly scoped native DNS automation can also suit an existing deployment.

Client guides and application sources

Traefik full configuration · Certbot hooks · Certbot Docker · win-acme PowerShell · AI setup assistant. Complete subscriber assets require active paid access. For native certificate imports, use the application’s deployment documentation and a suitable certificate-deployment hook.

• Stalwart Mail Server project website ↗
• Stalwart Mail Server endpoint and deployment source ↗
• Stalwart Mail Server configuration reference ↗
• Traefik ACME DNS challenge reference ↗

Source review: 2026-11-08. Product versions and deployment packaging change; verify the actual listener and application settings before applying the example.

Software summary from Awesome-Selfhosted’s Stalwart Mail Server record, licensed CC BY-SA 3.0. Gateway instructions and illustration by SimpleACME. No vendor affiliation is claimed.