Please review /etc/httpd/conf.d/phpwapmail.conf
phpwapmail-0.9.4-5.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/phpwapmail-0.9.4-5.fc18
Package phpwapmail-0.9.4-5.fc18: * should fix your issue, * was pushed to the Fedora 18 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing phpwapmail-0.9.4-5.fc18' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2012-17336/phpwapmail-0.9.4-5.fc18 then log in and leave karma (feedback).
phpwapmail-0.9.4-5.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.