By default, Devise sends all emails synchronously with deliver_now.

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To change that, Devise's readme suggests overwriting the send_devise_notification method like this:

class User

  def send_devise_notification(notification, *args)
    devise_mailer.send(notification, self, *args).deliver_later
  end
  
end

However, there is one problem: When deliver_later enqueues the mail with ActiveJob, the job arguments are logged. In case of a password reset, this includes the password reset token, which should not be logged.

ActiveJob's logs can be disabled per job, so you can do this:

class ApplicationMailDeliveryJob < ActionMailer::MailDeliveryJob
  self.log_arguments = false
end

class ApplicationMailer # (or any other mailer that the devise mailer inherits from, see devise configuration)
  self.delivery_job = ApplicationMailDeliveryJob
end

With this configuration, you can send asynchronous mail without logging sensitive parameters and everyone is happy :)