---
title: "Rails 5.2 allows mailers to use custom Active Job class"
description:
  "Rails now allows to configure a job class for a mailer so that we can use
  custom Active Job classes per mailer"
canonical_url: "https://www.bigbinary.com/blog/rails-5-2-allows-mailers-to-use-custom-active-job-class"
markdown_url: "https://www.bigbinary.com/blog/rails-5-2-allows-mailers-to-use-custom-active-job-class.md"
---

# Rails 5.2 allows mailers to use custom Active Job class

Rails now allows to configure a job class for a mailer so that we can use custom
Active Job classes per mailer

- Author: Prathamesh Sonpatki
- Published: January 15, 2018
- Categories: Rails 5.2, Rails

Rails allows sending emails asynchronously via Active Job.

```ruby
Notifier.welcome(User.first).deliver_later
```

It uses `ActionMailer::DeliveryJob` as the default job class to send emails.
This class is
[defined internally](https://github.com/rails/rails/blob/7b4132f4a28d1c264a972b95bf86bf6230869a40/actionmailer/lib/action_mailer/delivery_job.rb#L10)
by Rails.

The `DeliveryJob` defines `handle_exception_with_mailer_class` method to handle
exception and to do some housekeeping work.

```ruby
def handle_exception_with_mailer_class(exception)
  if klass = mailer_class
    klass.handle_exception exception
  else
    raise exception
  end
end
```

One might need more control on the job class to retry the job under certain
conditions or add more logging around exceptions.

Before Rails 5.2, it was not possible to use a custom job class for this
purpose.

Rails 5.2 has added a feature to
[configure the job class per mailer](https://github.com/rails/rails/pull/29457).

```ruby
class CustomNotifier < ApplicationMailer
  self.delivery_job = CustomNotifierDeliveryJob
end
```

By default, Rails will use the internal `DeliveryJob` class if the
`delivery_job` configuration is not present in the mailer class.

Now, Rails will use `CustomNotifierDeliveryJob` for sending emails for
CustomNotifier mailer.

```ruby
CustomNotifier.welcome(User.first).deliver_later
```

As mentioned above `CustomNotifierDeliveryJob` can be further configured for
logging, exception handling and reporting.

By default, `deliver_later` will pass following arguments to the `perform`
method of the `CustomNotifierDeliveryJob`.

- mailer class name
- mailer method name
- mail delivery method
- original arguments with which the mail is to be sent

```ruby
class CustomNotifierDeliveryJob < ApplicationJob

  rescue_from StandardError, with: :handle_exception_with_mailer_class

  retry_on CustomNotifierException

  discard_on ActiveJob::DeserializationError

  def perform(mailer, mail_method, delivery_method, *args)
    logger.log "Mail delivery started"
    klass = mailer.constantize
    klass.public_send(mail_method, *args).send(delivery_method)
    logger.log "Mail delivery completed"
  end

  def handle_exception_with_mailer_class(exception)
    if klass = mailer_class
      klass.handle_exception exception
    else
      raise exception
    end
  end
end
```

We can also simply inherit from the `ActionMailer::DeliveryJob` and override the
retry logic.

```ruby
class CustomNotifierDeliveryJob < ActionMailer::DeliveryJob
  retry_on CustomNotifierException
end
```

## Links

- [Human page](https://www.bigbinary.com/blog/rails-5-2-allows-mailers-to-use-custom-active-job-class)