what you host did was set WHM/cPanel to not allow the USER 'nobody' to send emails.
that is a tweak that they did to stop your software from sending, in the interests of more 'security' for their server. it's their call, although they are really screwing you over by doing that.
what they really should do is run php as either suPHP or fastCGI, so that your php scripts run as the actual cPanel user account for your site.
if they won't budge on it, then move.
Tom @
Express hosting would have a setup that would run your forums much better and i highly recommend him
he'll even move you, since it's cPanel to cPanel and it will be quite painless.
