SMTP port for On-Prem on Google Compute Engine

  • 8 December 2016
  • 0 replies

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By default, Looker uses Sendgrid as a mail relay. This allows Looker to email Scheduled Looks to end users as well as send application errors to Looker. The default port for SMTP in Looker is 587 as specified in our documentation. In some cases, primarily in on-premise (non Looker hosted) instances, it may be necessary to change the default port so that you can continue to use SendGrid. You can do this in the startup options in the lookerstart.cfg file.

However, if you have an on-premise instance and you’re on the Google (virtual machine) Compute Engine platform you will not be able to default SMTP settings in the Looker UI without making a change to the startup-options in the lookerstart.cfg file.


Google Compute Engine does not allow outbound connections on ports 25, 465, and 587. By default, these outbound SMTP ports are blocked because of the large amount of abuse these ports are susceptible to. You must use port 2525 on Google Compute Engine.

To use 2525, you must add this command line in the Looker start-up options to change the default mailer port:



--default-mailer-port=<i> Port over which to send mail when using default mailer (default: 587)

Once, you have made this change, you will need to restart the instance for the change to take effect. Additionally, you can test by going to the SMTP page and clicking “Send Test Email”.

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