Issue with sending emails using Gmail - OpenTimeout (execution expired)

Hi,

I have installed GitLab Enterprise Edition 11.6.2-ee with a self signed certificate : the gitlab server is reachable via HTTPS.
I’m using SMTP configuration with Gmail account and i don’t receive the emails sent from myemail@gmail.com.
Below the configuration (gitlab.rb) and two debug tests with their results.

### Email configuration
gitlab_rails['gitlab_email_enabled'] = true
gitlab_rails['gitlab_email_from'] = 'myemail@gmail.com'
gitlab_rails['gitlab_email_display_name'] = 'ADM'
gitlab_rails['smtp_enable'] = true
gitlab_rails['smtp_address'] = "smtp.gmail.com"
gitlab_rails['smtp_port'] = 587
gitlab_rails['smtp_user_name'] = "myemail@gmail.com"
gitlab_rails['smtp_password'] = "passpass"
gitlab_rails['smtp_domain'] = "smtp.gmail.com"
gitlab_rails['smtp_authentication'] = "login"
gitlab_rails['smtp_enable_starttls_auto'] = true
gitlab_rails['smtp_tls'] = true
gitlab_rails['smtp_openssl_verify_mode'] = 'peer'

I tried debug console, but i can’t detect the issue :

gitlab-rails console
Command 1: Check STMP configuration
irb(main):001:0> ActionMailer::Base.smtp_settings
Result:
=> {:authentication=>:login, 
    :address=>"smtp.gmail.com", 
    :port=>587, 
	:user_name=>"myemail@gmail.com",
    :password=>"passpass", 
	:domain=>"smtp.gmail.com", 
	:enable_starttls_auto=>true, 
	:tls=>true, 
	:openssl_verify_mode=>"peer", 
	:ca_file=>"/opt/gitlab/embedded/ssl/certs/cacert.pem"}
Command 2 : Sending email test
irb(main):002:0> Notify.test_email('myemail@gmail.com', 'Hello World', 'This is a test message').deliver_now

Result 2 :
Notify#test_email: processed outbound mail in 250.2ms
Sent mail to myemail@gmail.com (30014.9ms)
Date: Mon, 20 May 2019 17:15:49 +0200
From: MAP <myemail@gmail.com>
Message-ID: <5ce2c4a5c7683_274703fa3eafdc5f091214@mydomain.mail>
Subject: Hello World
Mime-Version: 1.0
Content-Type: text/html;
 charset=UTF-8
Content-Transfer-Encoding: 7bit
Auto-Submitted: auto-generated
X-Auto-Response-Suppress: All

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html><body><p>This is a test message</p></body></html>

Traceback (most recent call last):
       16: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/actionmailer-5.0.7/lib/action_mailer/base.rb:541:in `deliver_mail'
       15: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/activesupport-5.0.7/lib/active_support/notifications.rb:164:in `instrument'
       14: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/activesupport-5.0.7/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
       13: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/activesupport-5.0.7/lib/active_support/notifications.rb:164:in `block in instrument'
       12: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/actionmailer-5.0.7/lib/action_mailer/base.rb:543:in `block in deliver_mail'
       11: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/mail-2.7.0/lib/mail/message.rb:260:in `block in deliver'
       10: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/mail-2.7.0/lib/mail/message.rb:2160:in `do_delivery'
        9: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/mail-2.7.0/lib/mail/network/delivery_methods/smtp.rb:100:in `deliver!'
        8: from /opt/gitlab/embedded/lib/ruby/gems/2.5.0/gems/mail-2.7.0/lib/mail/network/delivery_methods/smtp.rb:109:in `start_smtp_session'
        7: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:518:in `start'
        6: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:548:in `do_start'
        5: from /opt/gitlab/embedded/lib/ruby/2.5.0/timeout.rb:103:in `timeout'
        4: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:549:in `block in do_start'
        3: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:539:in `tcp_socket'
        2: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:539:in `open'
        1: from /opt/gitlab/embedded/lib/ruby/2.5.0/net/smtp.rb:539:in `initialize'
Net::OpenTimeout (execution expired)

Best regard

Any suggestions ?