I'd like to use it on my RHEL6. Thanks.
milter-greylist-4.5.7-1.el6 has been submitted as an update for Fedora EPEL 6. https://admin.fedoraproject.org/updates/milter-greylist-4.5.7-1.el6
Package milter-greylist-4.5.7-1.el6: * should fix your issue, * was pushed to the Fedora EPEL 6 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=epel-testing milter-greylist-4.5.7-1.el6' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-EPEL-2014-0103/milter-greylist-4.5.7-1.el6 then log in and leave karma (feedback).
milter-greylist-4.5.7-1.el6 has been pushed to the Fedora EPEL 6 stable repository. If problems still persist, please make note of it in this bug report.