Thanks for your quick reply. I've tried doing what you wrote, but it has not worked. I even tried restarting apache, and sendmail multiple times in conjunction with the ini settings. Can you offer any further help? perhaps the header from an e-mail with the wrong "From"?
I haven't looked at the code but I suspect that this is an issue with the way the ezmail system intergrates with the local mail configuration (via the mail function I suspect).
I suspect you are using sendmail for delivery and not SMTP. I _think_ this would be an issue of the Envelope address Vs the Header address. Have you tried switching to using SMTP?
See http://www-uxsup.csx.cam.ac.uk/~jw35/docs/php-mail.html for an explainatiopn of 'Envelope' vs 'Header' address.