recipient_interceptor

Use this Ruby gem to avoid emailing your users from non-production environments.

# Gemfile
gem "recipient_interceptor"

# config/environments/staging.rb
Mail.register_interceptor(
  RecipientInterceptor.new("staging@example.com")
)

# config/environments/production.rb
My::Application.configure do
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address: ENV.fetch("SMTP_ADDRESS"), # example: "smtp.sendgrid.net"
    authentication: :plain,
    domain: ENV.fetch("SMTP_DOMAIN"), # example: "heroku.com"
    enable_starttls_auto: true,
    password: ENV.fetch("SMTP_PASSWORD"),
    port: "587",
    user_name: ENV.fetch("SMTP_USERNAME")
  }
end

Email will be intercepted and delivered to the provided address with headers X-Intercepted-To, X-Intercepted-Cc, and X-Intercepted-Bcc added.

Configuration options and examples

Deliver intercepted email to multiple email addresses:

Mail.register_interceptor(
  RecipientInterceptor.new(["one@example.com", "two@example.com"])
)

Use a comma-delimited string:

Mail.register_interceptor(
  RecipientInterceptor.new("one@example.com,two@example.com")
)

Use an environment variable:

# heroku config:set EMAIL_RECIPIENTS="one@example.com,two@example.com" --app staging
Mail.register_interceptor(
  RecipientInterceptor.new(ENV["EMAIL_RECIPIENTS"])
)

Prefix the subject line with static text:

Mail.register_interceptor(
  RecipientInterceptor.new(
    ENV["EMAIL_RECIPIENTS"],
    subject_prefix: "[staging]",
  ),
)

Prefix the subject line with contents from the original message:

Mail.register_interceptor(
  RecipientInterceptor.new(
    ENV["EMAIL_RECIPIENTS"],
    subject_prefix: proc { |msg| "[staging] [#{(msg.to + msg.cc + msg.bcc).sort.join(",")}]" }
  ),
)

The object passed to the proc is an instance of Mail::Message.

Alternatives

Postmark's Sandbox mode

Contributing

Fork the repo.

bundle
bundle exec rake

Make a change. Run tests. Open a pull request. Discuss/address any feedback with maintainer. Maintainer will merge.