Problem with implicit multipart emails using ActionMailer in Rails 2.3.3

With earlier versions of Rails ActionMailer used to implicitly send multipart (text/plain and text/html) email messages for me, but it looks like now it's sending two text/plain parts.

Simplified details:

Here's my model:

class Notifications < ActionMailer::Base   def confirmation(sent_at =     @subject = 'Thank you for registering'     @body = {}     @recipients = ''     @from = ''     @sent_on = sent_at     @headers = {}   end end

I have two views called confirmation.text.plain.erb and confirmation.text.html.erb

In a unit test, for debug purposes, I have:   sent = Notifications.create_confirmation   puts sent.to_s

The resulting message looks like this: