Email Responder (Spam.exe)

I wonder if you could help me, we’ve been successfully using Jana Server and Spam.exe as a email responder for several years, however the responder has just recently stopped responding. It is configured correctly and does send a respond message when emails are sent internally. It appears however when received from our ISP, Spam.exe is having problems, below is a typical error message in the repsonde.log. I can configure Jana to work with a different ISP POP3 email account and the Responder works ok, however i need to have it work with a our main business ISP emails. We are running Jana 2.5.0.133 and Spam.exe 2.5.7.3. I know our ISP had been working on new security and wondered if they had changed or modified the email header that now caused Spam a problem. I'm awaiting feedback from our ISP. Spam.exe is quite old now, are there any other programs that offer a similar Responder feature?

Responde.log;

08/12/2009 09:05:24 No email returned. Reason: Risk of infinite loop!
received-spf: none identity=helo; client-ip=65.55.90.27; receiver=mx.pcl-ipin01.plus.net; envelope-from="xxxxx@hotmail.com"; x-sender="postmaster@snt0-omc1-s16.snt0.hotmail.com"; x-conformance=sidf_compatible gefunden / Keine Rückantwort erzeugt