Sudden problem: content-filter MTA-Blocked

[yonatan]

I've got a mysterious problem that occurred today and is causing a lot of trouble.

When my users send an email to <faxnumber>@fax.mydomain.com it is no longer being relayed to a faxserver on the LAN! The users are getting the following email from postmaster@mydomain.com:

Undeliverable mail, MTA-BLOCKED

The message WAS NOT relayed to:
<1234@fax.mydomain.com>: [127.0.0.1] said:
554 5.4.0 Failed, id=19475-04, from MTA([127.0.0.1]:10025): 554 5.4.0 Error: too many hops

This nondelivery report was generated by the program amavisd-new at host
zcs.mydomain.com. Our internal reference code for your message is
19475-04/W1w3XIHjizit

It has been working perfectly for a couple of weeks and suddenly this happens.

I honestly don't know how to troubleshoot and looking for some enlightenment from the Zimbra gurus on here

Thanks

[yonatan]

I looked up the SMTP NDR code and it says that 5.4.0:

DNS Problem. Check the Smart host, or check your DNS. It means that there is no DNS server that can resolve this email address. Could be Virtual Server SMTP address.

I haven't made any changes to my DNS server running on the same Zimbra host, but just in case I restarted bind. HOWEVER, it hasn't resolved the problem.

I've got to fix this before tomorrow morning. Please help.

[yonatan]

As I don't have a clue how to fix this, I thought I'd restart everything with zmcontrol restart. Nonetheless, it hasn't solved anything, so I'm back to square one.