Can not Send mail when create user

Hi, I'm using centos6.7 and gitlab version is 8.6.2 my gitlab can't send mail in the gitlab.rb setting like this:

gitlab_rails['gitlab_email_from'] = 'mymail' gitlab_rails['gitlab_email_reply_to'] = 'mymail'

gitlab_rails['smtp_enable'] = true gitlab_rails['smtp_address'] = "our smtp server" gitlab_rails['smtp_port'] = 25 gitlab_rails['smtp_user_name'] = "accout" gitlab_rails['smtp_password'] = "password" gitlab_rails['smtp_domain'] = "our domain" gitlab_rails['smtp_authentication'] = false gitlab_rails['smtp_enable_starttls_auto'] = false gitlab_rails['smtp_tls'] = false gitlab_rails['smtp_openssl_verify_mode'] = 'peer'

and I follow the log in /sidekiq/current to see:

ActionMailer::DeliveryJob JID-09b3cfce156f412d1fede0de INFO: start ActionMailer::DeliveryJob JID-09b3cfce156f412d1fede0de INFO: fail: 0.039 sec WARN: {"class"=>"ActiveJob::QueueAdapters::SidekiqAdapter::JobWrapper", "wrapped"=>"ActionMailer::DeliveryJob", "queue"=>"mailers", "args"=>............ WARN: ArgumentError: wrong authentication type false WARN: /opt/gitlab/embedded/lib/ruby/2.1.0/net/smtp.rb:771:in `check_auth_method'

How can I fix it to let email working??