501 Syntactically invalid HELO argument(s)


  • Used Zammad version: latest docker image as of 31.03.2021
  • Used Zammad installation source: (source, package, …) docker-compose inside docker-swarm
  • Operating system: docker
  • Browser + version: 89.0.774.63 (64-Bit) (MS Edge)

Expected behavior:

  • I enter the SMTP Host without username and password and change the SMTP Port to 25 to be able setup zammad on first installation. This SMTP Host is just available in my network and not on WAN.

Actual behavior:

Steps to reproduce the behavior:

  • install docker-compose images on docker-swarm by just replacing all the env variables with “normal” written ones and set the version up to 3.8

anyone have an idea how to fix this?

These are the relevant documentation parts:

Just a wild guess, your FQDN is not example.com but example.com:1234 which is not a correct EHLO or FROM address. Your mail server will not like that idea, so skip that step with “sendmail” and configure it later as suggested in the docs.

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