> Im 99.999% certain its not PHP. The configuration is bog standard
> regardless, you just set the sendmail_path variable and thats it. Its
> calling exim as evidenced by looking at the process list, so it would seem
> its an exim issue, something is causing exim to reject the request, but i
> dont know what! it would help if it wrote something to the log
You could try phpmailer[1], this can talk SMTP directly..
Also, have you tried to su to the user php is running as before running exim?
[1]
http://phpmailer.sourceforge.net/
Regards,
Donovan