“Need help configuring SMTP listeners and MailWizz integration on production setup”

KumoMTA Integrations
1

Hi team :waving_hand:

I’m setting up KumoMTA for production on a VDS with MailWizz and running into an SMTP listener issue (ports 25 / 2525 not binding).

Here are my setup details:

  • OS: Ubuntu 22.04 x64
  • KumoMTA version: 2025.10.06-5ec871ab
  • Control Panel: MailWizz (self-hosted)
  • Hostname: mtal.engagepuls.com
  • IPs: 1 VDS with 4 dedicated IPs (for IP rotation / pool setup)
  • Purpose: Bulk + transactional sending
  • Issue:
    • Service starts, HTTP listener works (0.0.0.0:8000),
    • But SMTP listeners (25 / 2525) fail — no ports open.
    • journalctl shows:
      deserialize error: unknown field `idle_timeout`
while processing {"listen":"0.0.0.0:25","hostname":"mtal.engagepuls.com","idle_timeout":"300s"}
    • Removing that field lets the service start, but still no SMTP binding visible.
      Ensuring MailWizz can connect properly for SMTP relaying

General tuning and verification for best deliverability

Please let me know the best way to proceed

I’d appreciate guidance on:

  • Correct listener syntax for the new version
  • Example production-ready config (IP pools, DKIM, shaping, etc.)
  • Proper MailWizz connection setup

Thanks a lot in advance :folded_hands:
Tagging @Mike Hillyer for visibility.

3

That error would suggest that you used AI to build the config so I would guess that you have many other issues as well.
Please follow the instructions above and include all your configs, or no one can help you.
We also offer paid consulting (see link above) but we will still need to see all your configs in order to help.