before_send and after_send callbacks are shared across classes

[tonydewan]

class ResetPasswordEmail < ActiveMailer::Base
  before_send :do_a_thing
  
  def do_a_thing
  end
end

class InviteUserEmail < ActiveMailer::Base
end

InviteUserEmail.before_send_actions
=> [:do_a_thing]

[esquivalient]

The solution here is to stop using cattr in base and define the accessors using

class << self
  attr_accessor :before_send_actions
end

because cattr alters the parent: https://apidock.com/rails/Class/cattr_accessor.

I hand tested this solution.