Added systemd unit file

Makefile

-all:
+all: cyrus-imapd-service
 	tar xf cyrus-imapd-3.2.3.tar.gz
 	cd cyrus-imapd-3.2.3 && ./configure --prefix=/usr
 	$(MAKE) -C cyrus-imapd-3.2.3
 	$(MAKE) -C cyrus-imapd-3.2.3 install
+	@echo "$$CYRUS_IMAPD_SERVICE" > /lib/systemd/system/cyrus-imapd.service
+	systemctl enable cyrus-imapd.service
 	rm -rf cyrus-imapd-3.2.3
+
+cyrus-imapd-service:
+define CYRUS_IMAPD_SERVICE
+[Unit]
+Description=Cyrus-imapd IMAP/POP3 email server
+After=local-fs.target network.target
+
+[Service]
+Type=simple
+ExecStart=/usr/libexec/master
+PrivateTmp=true
+
+# Cyrus may spawn many processes in normal operation.  These figures are higher
+# than the defaults, but may still need to be tuned for your local
+# configuration.
+TasksMax=2048
+LimitNOFILE=16384
+
+[Install]
+WantedBy=multi-user.target
+endef
+export CYRUS_IMAPD_SERVICE