False positives on spam filters

[Dave A]

False positives on spam filters are driving me nuts. It gets even better when they bounce your message and don't tell you why.

I get this from Content-filter at spamwall19.mweb.co.za (I'm tempted to include their email address so that they can really get spammed):

A message from <my email address> to:
-> client@ens.mweb.co.za
-> client@yebo.co.za

was considered unsolicited bulk e-mail (UBE).

Our internal reference code for your message is (series of numbers)

The message carried your return address, so it was either a genuine mail from you, or a sender address was faked and your e-mail address abused by third party, in which case we apologize for undesired notification.

We do try to minimize backscatter for more prominent cases of UBE and for infected mail, but for less obvious cases of UBE some balance between losing genuine mail and sending undesired backscatter is sought, and there can be some collateral damage on both sides.

First upstream SMTP client IP address: [196.25.240.74] ctb-mesg4.saix.net

No Spam Assasin type report as to how you offended the system - nutting.

I've run over the header report and it is as plain as day the message was generated by Outlook, not a bulk mailer. The originating IP address is in the block range of my SPF record. So what was the problem?

Is this what they mean when saying an SPF record is a problem with mail forwarders? Because in this case the mail to yebo (which is what was provided by the client) was forwarded to mweb. Now I can't control that - from my end how the heck can I even see it coming?

And of course the client is ticked off that the email hasn't gone through. And is not accepting that it is their email service that is the problem!