Use external SMTP server with Redmine

[alexm]

Is there a way to configure redmine to use external SMTP server, different from my Cloudron domain?

I have tried doing it editing additionl_envrionment.rb file, added there lines like
config.action_mailer.delivery_method = :smtp

config.action_mailer.smtp_settings = {
  address:              'smtp.service.com',
  port:                 587,
  domain:               'mydomain.com.au',
  authentication:       :login,
  user_name:            'me@domain.com.au',
  password:             File.read('/app/data/mypassword').strip,
  enable_starttls_auto: true
}

But it didn't work, redmine ignored that settings and tried to send email via cloudron anyway.