diff --git a/port-check.sh b/port-check.sh
new file mode 100755
index 00000000..5ab28883
--- /dev/null
+++ b/port-check.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+
+. mailcow.conf
+
+for port in ${SMTP_PORT} ${SMTPS_PORT} ${SUBMISSION_PORT} ${IMAP_PORT} ${IMAPS_PORT} ${POP_PORT} ${POPS_PORT} ${SIEVE_PORT} 443; do
+	if [[ ! -z $(ss -tlnp "( sport = :$port )" 2> /dev/null | grep LISTEN | grep -vi docker) ]]; then
+		echo "Port $port is in use by other process."
+		err=1
+	fi
+done
+
+if [[ ${err} == "1" ]]; then
+	echo
+	echo "Exiting."
+	exit 1
+fi
+
+exit 0