Image Email Attachments Not Working

I'm been struggling with an email attachment problem for a few weeks
now. I can't seem to get image attachments in an email to work. I'd
receive the email fine, but the actual image in the attachment is broken
(the actual image data never gets sent).

[snip]

Mailer model
-------------------------------------------
def images_with_attachments()
     @subject = "test Subject
     @body = {:body => "this is testing text"}
     @recipients = "two2twelve@gmail.com"
     @from = "support@xmgimage.com"
  attachment :content_type => "image/jpg", :filename => "TestImage.jpg",
:body => File.read(RAILS_ROOT + "/public/images/TestImage.jpg")
end

According to the documentation[1], the :content_type should be "image/jpeg" not "image/jpg". Perhaps that's the problem?

And is the :filename necessary?

Regards,
Andy Stewart

[1] http://api.rubyonrails.org/classes/ActionMailer/Base.html