EDIT: Solved, check Brkdncr@lemmy.world’s comment below.

So, I am currently in the process of setting up a PeerTube and Lemmy instance, both on a dedicated Server running Debian 12. PeerTube seems to work properly by now, but the SMTP settings for Lemmy have been a bit of a headscratcher, and I wasn’t able to find a solution.

To set up Lemmy, I followed the “from scratch” guide, and, besides the mail issue, it seems like everything else is working so far.

Note that I am currently in the process of learning-by-doing with this whole project. So, I would not rule out, that I may have overlooked something really obvious and stupid, sorry for taking your time, then.

My settings in /opt/lemmy/lemmy-server/lemmy.hjson:

  email: {
    # Hostname and port of the smtp server
    smtp_server: "localhost:587"
    # Login name for smtp server
    smtp_login: "lemmymail"
    # Password to login to the smtp server
    smtp_password: "REDACTED"
    # Address to send emails from, eg "noreply@your-instance.com"
    smtp_from_address: "noreply@abnormalbeings.space"
    # Whether or not smtp connections should use tls. Can be none, tls, or starttls
    tls_type: "starttls"
  }

The error message I get, when trying both resetting a password, or applying as a new user:

WARN Error encountered while processing the incoming HTTP request: lemmy_server::root_span_builder: EmailSendFailed: Connection error: Connection error: invalid peer certificate: NotValidForName

“lemmymail” exists as a local user on the server.

# dovecot --version 2.3.19.1 (9b53102964)

If needed, I can provide additional info from dovecot and/or postfix configurations in the backend. Similar settings as above have worked for PeerTube. As a reference - these are working in production.yaml there:

# SMTP server to send emails
smtp:
  # smtp or sendmail
  transport: smtp
  # Path to sendmail command. Required if you use sendmail transport
  sendmail: null
  hostname: mail.abnormalbeings.space
  port: 587 # If you use StartTLS: 587
  username: 'peertube@abnormalbeings.space'
  password: 'REDACTED'
  tls: false # If you use StartTLS: false
  disable_starttls: false
  ca_file: null # Used for self signed certificates
  from_address: 'peertube@abnormalbeings.space'

Things I have tried:

• Changing the user from and to a user with @abnormalbeings.space in the string
• Changing the user to one I know works, as I use them for automatic PeerTube mail messages
• Changing the hostname to a FQDN url instead of localhost (without https://)
• Trying different ports (did not expect that to work)
• changing tls_type to “none”
• changing the Password to one containing no special characters (and back)
• changing smtp_from_address to an actually existing user
• restarting nginx, dovecot, postfix, lemmy-server and lemmy-ui for good measure after every change