Net::SMTPAuthenticationError when sending email from Rails app (on staging environment)

I am sending email from my Rails application. It works well on development environment, but fails on staging. I get the following error:

Net::SMTPAuthenticationError (534-5.7.14 <

Note, that my I don't have a domain name for my staging.

Here are my settings in staging.rb

config.action_mailer.delivery_method = :smtp
config.action_mailer.default_url_options = { :host => "" }
config.action_mailer.smtp_settings = {
      :address => "",
      :port => 587,
      :domain => ''
      :user_name => "",
      :password => "my_email_password",
      :authentication => 'login'

Please, help.


After adding :tls => true option I get

OpenSSL::SSL::SSLError (Unrecognized SSL message, plaintext connection?)

And then I changed port to 25 and now I get this (with 30 seconds delay):

Timeout::Error (execution expired)


I had the same problem: emails were sent from development, but not from production (where I was getting Net::SMTPAuthenticationError). This drove me to conclusion that the problem was not with my app's configuration, but with Google.

Reason: Google was blocking access from unknown location (app in production)

Solution: Go to and click continue (this will grant access for 10 minutes for registering new apps). After this my app in production started sending emails ;)

This solution is working for me:

config.action_mailer.delivery_method = :smtp
  config.action_mailer.default_url_options = { host:'localhost', port: '3000' }
  config.action_mailer.perform_deliveries = true
  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.default :charset => "utf-8"
  config.action_mailer.smtp_settings = {
      :address => "",
      :port => 587,
      :domain => 'localhost:3000',
      :user_name => "",
      :password => "password",
      :authentication => :plain,
      :enable_starttls_auto => true

It's true that Google will block your sign-in attempt but You can change your settings at so that your account is no longer protected by modern security standards.

Solved! I simply changed password for my gmail account and somehow errors disappeared.

After dozen of changes, the final settings I ended up with are:

config.action_mailer.delivery_method = :smtp
config.action_mailer.default_url_options = { :host => "" }
config.action_mailer.smtp_settings = {
      :address => "",
      :port => 587,
      :domain => '',
      :user_name => "",
      :password => "my_email_password",
      :authentication => :plain,
      :enable_starttls_auto => true

go to following link and turn on

The above solution provided the correct settings (which I already had) but did not solve the issue. After continued attempts, I kept getting the same error. Turns out, I had to "clear the CAPTCHA" from the web. See the gmail documentation for details.

You can also jump right to the "clear the CAPTCHA" page here.

A lot later but just in case it helps anyone.. Just called Google Apps Help Center and they instructed to change the lesssecureapps setting (as everyone else) but also to change the port to 465.

In my case, that did the trick!

Hello this also worked for me and so if someone is still having a problem try this out.

Make sure you have figaro in your gemfile. To save sensitive information such as username and password as environment variables

gem 'figaro'

And in your config/environments/development.rb , paste the codes below using smtp as method delivery

 config.action_mailer.delivery_method = :smtp

SMTP settings for gmail

  config.action_mailer.smtp_settings =
    :address=> "",
    :port => 587,
    :user_name => ENV['gmail_username'],
    :password=> ENV['gmail_password'],
    :authentication=> "plain",

config.action_mailer.default_url_options = { host: "locahost:3000" }

In your config directory create a file called application.yml and add the codes below.

gmail_username: '' 
gmail_password: "your_example_email_password_here"

You must use your email and password for authentication in the file.

I also faced the problem, and after some research in Gmail setting, I found the solution:

  1. In gmail, go to settings.

  2. Select "Forwarding and POP/IMAP" tab.

  3. In the IMAP access section, select "Enable IMAP".

The accepted answer seems very old, I don't know if at that time the followin (better) solution was existing:

Now, sending emails works perfectly!

I had the same problem.


I had the same problem and after some trial and errors, have come to this resolution which is an option to be enabled in google:


Enable 'Access for less secure apps' here by logging in with the email address you have provided in smtp configuration.

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