Workaround for: Message rejected due to DMARC policy for yahoo.com

Question

Using Drupal 7 on CentOS 6 with stock Postfix 2.6.6 and since recently any mails sent by Drupal on behalf of users with @yahoo.com mail addresses are bounced hard:

Diagnostic-Code: smtp; 550 5.7.1 Message rejected due to DMARC policy for
    yahoo.com

And also:

Message not accepted for policy reasons.  See
    http://postmaster.yahoo.com/errors/postmaster-28.html (in reply to end of
    DATA command)

I think this is result of Yahoo changing its mail policy, so that all other big mail providers participating in DMARC (like Gmail or Mail.ru or ...) only accept @yahoo.com senders from Yahoo mail servers (and thus not from my little Drupal website).

Has anyone affected by this change found a good workaround on the Drupal site for this problem?

UPDATE:

My Postfix installation works well and is not the problem.

The problem with Yahoo users should be solved in Drupal hook for sending contact and registration mails. I think (from reading Yahoo docs) the "From" header there should be replaced by "Reply-To" or something similar.

Note: My question affects Drupal and has to be solved with Drupal means (which is why IMO it belongs in this SE-site).