Rails 5 allows configuring queue name for mailers

In Rails 4.2, Active Job was integrated with Action Mailer to send emails asynchronously.

Rails provides deliver_later method to enqueue mailer jobs.

class UserMailer < ApplicationMailer
  def send_notification(user)
    @user = user
    mail(to: user.email)
  end
end

> UserMailer.send_notification(user).deliver_later
=> <ActionMailer::DeliveryJob:0x007ff602dd3128 @arguments=["UserMailer", "send_notification", "deliver_now", <User id: 1, name: "John", email: "[email protected]">], @job_id="d0171da0-86d3-49f4-ba03-37b37d4e8e2b", @queue_name="mailers", @priority=nil>

Note that the task of delivering email was put in queue called mailers.

In Rails 4.x, all background jobs are given queue named "default" except for mailers. All outgoing mails are given the queue named "mailers" and we do not have the option of changing this queue name from "mailers" to anything else.

Since Rails 4.x comes with minimum of two queues it makes difficult to use queuing services like que which relies on applications having only one queue.

Customizing queue name in Rails 5

In Rails 5, we can now change queue name for mailer jobs using following configuration.

config.action_mailer.deliver_later_queue_name = 'default'

class UserMailer < ApplicationMailer
  def send_notification(user)
    @user = user
    mail(to: user.email)
  end
end

2.2.2 :003 > user = User.last
=> <User id: 6, name: "John", email: "[email protected]">

2.2.2 :004 > UserMailer.send_notification(user).deliver_later
=> <ActionMailer::DeliveryJob:0x007fea2182b2d0 @arguments=["UserMailer", "send_notification", "deliver_now", <User id: 1, name: "John", email: "[email protected]">], @job_id="316b00b2-64c8-4a2d-8153-4ce7abafb28d", @queue_name="default", @priority=nil>