Modify the SMTP config parameters in /etc/gitlab/gitlab.rb
gitlab_rails['smtp_enable'] = true
gitlab_rails['smtp_address'] = "mailserver.example.com"
gitlab_rails['smtp_port'] = 465
gitlab_rails['smtp_user_name'] = "smtp user"
gitlab_rails['smtp_password'] = "smtp password"
gitlab_rails['smtp_domain'] = "example.com"
gitlab_rails['smtp_authentication'] = "login"
gitlab_rails['smtp_enable_starttls_auto'] = false
gitlab_rails['smtp_openssl_verify_mode'] = 'peer'Test by entering into the Rails Console and issuing the following command
Notify.test_email('recipient@example.com', 'Message Subject', 'Message Body').deliver_now