Email not working from within GitLab

I am able to send a test email from gitlab-rails console:
irb(main):003:0> Notify.test_email('destination_email@address.com', 'Message Subject', 'Message Body').deliver_now

However, I am not receiving email from the GitLab application.
Neither...
/var/log/gitlab/gitlab-rails/sidekiq.log -or- /var/log/gitlab/gitlab-rails/production.log
...indicate that mail has been sent.

Ideas? ;-)

THX!

JWS