Hi, There is the complete patch to support systemd.
diff -urN nullmailer-1.13/debian/control nullmailer/debian/control --- nullmailer-1.13/debian/control 2014-08-06 23:42:09.000000000 +0300 +++ nullmailer/debian/control 2015-11-06 09:52:49.580025701 +0300 @@ -2,7 +2,7 @@ Section: mail Priority: extra Maintainer: Nick Leverton <n...@leverton.org> -Build-Depends: debhelper (>= 9), po-debconf, automake, autoconf, +Build-Depends: debhelper (>= 9), dh-systemd, po-debconf, automake, autoconf, dh-autoreconf, libgnutls28-dev | libgnutls-dev Standards-Version: 3.9.5 Homepage: http://untroubled.org/nullmailer/ diff -urN nullmailer-1.13/debian/rules nullmailer/debian/rules --- nullmailer-1.13/debian/rules 2014-08-07 11:13:12.000000000 +0300 +++ nullmailer/debian/rules 2015-11-06 09:52:29.963799827 +0300 @@ -13,7 +13,7 @@ export DEB_BUILD_MAINT_OPTIONS = hardening=+all %: - dh $@ --with autoreconf + dh $@ --with autoreconf --with systemd override_dh_prep: dh_prep diff -urN nullmailer-1.13/debian/service nullmailer/debian/service --- nullmailer-1.13/debian/service 1970-01-01 03:00:00.000000000 +0300 +++ nullmailer/debian/service 2015-11-06 10:12:46.689953179 +0300 @@ -0,0 +1,11 @@ +[Unit] +Description=Mail Transport Agent + +[Service] +ExecStart=/usr/sbin/nullmailer-send +Restart=always +User=mail + +[Install] +WantedBy=multi-user.target +WantedBy=mail-transport-agent.target diff -urN nullmailer-1.13/debian/tmpfile nullmailer/debian/tmpfile --- nullmailer-1.13/debian/tmpfile 1970-01-01 03:00:00.000000000 +0300 +++ nullmailer/debian/tmpfile 2015-11-06 09:45:30.569589832 +0300 @@ -0,0 +1 @@ +p /var/spool/nullmailer/trigger 622 mail root