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EMail - SMTP TCP lookup not working

I tried to setup SMTP, but I get the error below. It looks like, it can’r resolve my adress?
I connected as root to the app container and could resolve mail.gmx.net.

Failure message:
Connection unsuccessful: Connection unsuccessful: SendMail: Failed to open connection., dial tcp: lookup mail.gmx.net on [::1]:53: dial udp [::1]:53: connect: cannot assign requested address


What are your SMTP settings set to?

Hello, @fendle

As mentioned by @amy.blais, the SMTP settings will be a good start to troubleshoot the issue here. You can either provide the screen shot with sensitive information redacted from System Console > Environment > SMTP or run the following command on the terminal of the server hosting Mattermost to get the information directly from config.json:

cat /opt/mattermost/config/config.json | grep -A30 "EmailSettings"
  • Based on this statement, can you please confirm the command that you use on the server terminal to resolve the connection to mail.gmx.net?
  • Additionally, did you run the Test Connection and verify if there are any errors reported?

  • Do you have any proxy / firewall that blocks the connection to reach out to mail.gmx.net?