A while back, I submitted dbmail/libsieve to Fedora-Extras for package review and inclusion. If you're interested in see these in more wide-spread use, or you run Fedora (*) and want to see packages more readily available, download the srpms located in the bug and make appropriate comments.
I don't currently have a sponsor, so if you are involved with Fedora-Extras and able to sponsor, please let me know. https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=216723 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=217497 (*) If it makes it into Fedora-Extras, it will probably make it into CentOS-Extras as well.
