ActionMailer not sending mail in development Rails 4

Why is this mailer not sending any mail? (Or any ideas for debugging?)

In my_app/config/environments/development.rb I have this code:

  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address:              'smtp.gmail.com',
    port:                 587,
    domain:               'my_app.com',
    user_name:            ENV['GMAIL_USERNAME'],
    password:             ENV['GMAIL_PASSWORD'],
    authentication:       'plain',
    enable_starttls_auto: true  }

Then on my local computer in ~/.bash_profile I have this code:

export GMAIL_USERNAME='blah@my_app.com'
export GMAIL_PASSWORD='***'

When I run $ env in my terminal, I see that both environment variables are correctly set.

I have also restarted my rails server.

You should add

config.action_mailer.perform_deliveries = true

as by default this is on false, preventing mails to be sent from your development environment...

For anyone not using smtp, switching the delivery method to sendmail helped me in addition to explicitly setting deliveries to be performed:

config.action_mailer.delivery_method = :sendmail

If you're having issues sending email from console, you have to call the deliver method on your mail.

MyMailer.create_email.deliver

All of these answers are great, but there is another place where you can get burned, especially in the context of debugging.

In development.rb make sure you set config.action_mailer.raise_delivery_errors = true

If your .deliver method seems to be working without issue, but you never actually receive the email across the wire, your delivery method may be throwing an exception and rails is swallowing the error. This is very true if you simply have something as simple as a misconfigured credentials, or an aws access denied API error. Save ripping your hair out and make sure you have raise_delivery_errors turned on. It wants to tell you something but can't.