Actionmailer ignores return-path setting

Hello,

i have the problem that i want to set the return-path to the envelope of outgoing emails so bounces can be handled. I tried to set the header as followed in my mailer class:

  def newsletter     subject 'subject'     reply_to 'donotreply@domain.com'     from 'from@domain.com'     recipients 'to@otherdomain.com'     sent_on Time.now     body :body => 'content'     headers 'return-path' => 'donotreply@domain.com'   end

However, in the outgoing email the return path is automatically set to 'from@domain.com'

I am using Rails 2.3.3 and Postfix 2.3

can anyone point me to the correct setting to set the return-path?

Greets -act