Huge Mail server problme !!! 550 Sender verify failed

[neo4242002]

mail@isp.com
    (generated from [email]enquiries@website.com[/email])
    SMTP error from remote mail server after RCPT TO:<mail@isp.com>:
    host mx.isp.com [1.1.1.1]: 550-Verification failed for <nobody@mydedicatedserver.com>
    550-REJECTED: Cannot route message
    550 Sender verify failed

all emails send from one of my client website suddenly get failed. but other websites on same server working fine. only difference I can see that this [website.com] has an SPF record and client use my server to verify email address when SMTP relay. I do not host any email account for this client. i collect all emails and send to mail@isp.com. this was working until 28 dec. but now al emails get failed and i get undeliverable mail failing like above and bellow. but only if that mails going through website PHP mail()

Verification failed for <nobody@mydedicatedserver.com>
    550-REJECTED: Cannot route message
    550 Sender verify failed

Verification failed for <nobody@mydedicatedserver.com>
    550-Unrouteable address
    550 Sender verify failed

Anyone can help please

[lloyd_tennison]

Are you forwarding the emails? If so, cannot have SPF. It specically says that in their FAQs. That will break forwarding. I would imagine this is it.

Does SPF break email forwarding?

Stuart Gathman's opinion is recorded at http://archives.listbox.com/spf-disc...0410/0488.html.

Yes, it does. You'll have to switch from forwarding, where the envelope sender is preserved, to remailing, where the envelope sender is changed. But don't worry, we're working on providing SRS patches for the four major opensource MTAs, so that when you upgrade to an SPF-aware version, this problem will be solved also.

http://www.openspf.org/faq.html#forwarding

Repackaging is a bad idea as then any SPAM repackaged looks like it is coming from your server.

[neo4242002]

But that was working until 28th Dec. 2005.

[Izzee]

Is the address you are sending it to mail@isp.com being blocked because of nobody@mydedicatedserver.com

If so there is a fix for the nobody@ issue which has become more and more common of late as more and more mail exchanges block this becuase it is a well known source of spam. Do a forum search for nobody@ as there is an exim tweak that will fix it and send mail out as username@mydedicatedserver.com. AOL and RR block addresses from nobody@ and lots more are joining the block club.

[lloyd_tennison]

But that was working until 28th Dec. 2005.

And how do you know the ISP did not change their SPF rules since?