DKIMPROXY signing issues


#1

Hello

we are using DKIMPROXY 1.2-3 for signing our outbound mails on Ubuntu 10.04. I setup this some month ago and at this time I was able to create my own test mails and send it to DKIM testers with correct results.
Setup is like:
Mail Client -> DKIMPROXY.out -> postfix -> INTERNET

I wrote a test script which creates an email and sends it to dkimproxy. (see attachment)
If I send an email to a tester I got a failed response

dkim=fail (body has been altered) header.i=@OURDOMAIN.net domainkeys=fail (message has been altered) header.from=user.name@OURDOMAIN.net

My guess is, that postfix changes/adds some headers.
But to get real confused. We are also sending our emails over this setup and depending on the receiver the DKIM is correct. These emails are generated by php and mail library.
Yahoo:

Authentication-Results: mta1224.mail.sk1.yahoo.com from=OURDOMAIN.net; domainkeys=pass (ok); from=OURDOMAIN.net; dkim=pass (ok)
AOL fails:

X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d014.1 ; domain : OURDOMAIN.net DKIM : fail

the most Postfix settings are default
Changes main.cf:

# dkimproxy content_filter= receive_override_options = no_unknown_recipient_checks,no_header_body_checks

How can I debug this to find out where the header changes happens?

Regards
stevie