Getting error "Remote domains not supported"

I am trying to send a message using the php library phpmailer from one of our debian web servers. I configure the script to use the mail() function, which apparently by default hands off the message to the local MTA if at all possible. The script itself reports successful delivery to exim, which I have confirmed by the following being found in '/var/log/exim4/mainlog':

"xxx@xxx.com R=nonlocal: Mailing to remote domains not supported"

It then ends up permanently rejected for delivery in 'www-data's local mailbox.

In this situation, how do I allow exim to send mail to any address at any domain? Is there a particular configuration directive (as I imagine there is) I need to be aware of?

The nonlocal router is unique to the Debian configuration. You should re-post this question to the Debian exim mailing list, which is documented in /usr/share/doc/exim4-base/README.Debian.gz

The OP has chosen a "local mail only" feature set and is now complaining about getting what he asked for.

The answer would be "dpkg-reconfigure exim4-config" and select a better suited profile.

Greetings