Please provide systemd unit file.
Please attach one, and I'll add it.
an example could be considered from here https://projects.archlinux.org/svntogit/community.git/tree/trunk?h=packages/opensmtpd
They should work as they run no kind of distro specific stuff
I will review, test and commit it in a week if nobody disagrees. Thanks
+*opensmtpd-5.3.3_p1-r1 (30 Aug 2013) + + 30 Aug 2013; Pacho Ramos <pacho@gentoo.org> +files/smtpd.service, + +files/smtpd.socket, +opensmtpd-5.3.3_p1-r1.ebuild, + opensmtpd-5.3.3.201308201232_p1.ebuild: + Add unit file (#470662 by Agostino Sarubbo) +