Gitlab SMTP settings with Zimbra Mail

If you would rather send application email via an SMTP server instead of via Sendmail or Postfix, add the following configuration information to /etc/gitlab/gitlab.rb and run

 gitlab-ctl reconfigure.

gitlab_rails['smtp_enable'] = true
gitlab_rails['smtp_address'] = 'mail.siteage.net'
gitlab_rails['smtp_port'] = 465
gitlab_rails['smtp_user_name'] = 'gitlab@domain.com'
gitlab_rails['smtp_password'] = 'password'
gitlab_rails['smtp_authentication'] = 'login'
gitlab_rails['smtp_enable_starttls_auto'] = false
gitlab_rails['gitlab_email_from'] = "gitlab@domain.com"
gitlab_rails['smtp_tls'] = true

https://docs.gitlab.com/omnibus/settings/smtp.html