Me too: Can't get SMTP to work (properly)


I am running my own rocketchat instance and my own mail server (mailcow). In order to enable Rockatchat to send out email, I have setup an account for it on my mail server. But I can’t get it to work:

The only port that it works at all is 25. I would rather use 587 but I keep getting an error message that I need to send a starttls command first. (That’s if I select IgnoreTLS; if I disable IgnoreTLS, I get an error message that the first certificate can’t be verified. I am using a Let’s Encrypt certificate, BUT: I can’t access my local mail server via the domain the certificate belongs to (due to rebinding protection from my firewall), so I access it directly via its local IP (to which the certificate does not belong). This approach (using 587 and ignoring the certificate) works for several other services I am running locally, but not for Rocketchat).

So my questions would be:

  • What does the toggle “pool” mean?
  • If I toggle “IgnoreTLS” on, does that disable TLS completely or does it only switch off validation of the certificate presented by the remote server (it sounds like the latter, but my experience points to the former…)?

If I use port 25, I can send emails to other local accounts (on my mail server) but not to accounts outside my mail server (other local services using port 587 for some reason do not have this limitation; I am guessing that this is a configuration issue on my mail server, so I am trying to replicate the settings for other services that work as intended as completely as possible, which includes using port 587).

Thnak you!

Server Setup Information

  • Version of Rocket.Chat Server: 4.3.1
  • Operating System: Debian 11
  • Deployment Method: docker-compose
  • Number of Running Instances: 1
  • DB Replicaset Oplog: enabled
  • NodeJS Version: 12.22.8
  • MongoDB Version: 4.4.12
  • Proxy: haproxy
  • Firewalls involved: pfsense

Any additional Information

Can't think of anything.

Any ideas?

I am now on 4.5.0 but it still doesn’t work.


I have a working dev setup with GitHub - docker-mailserver/docker-mailserver: Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.

Those parameters will usually vary for each mailserver.

At the end of the day, it will render a MAIL_URL environment variable for using with nodemailer