--- courier/module.esmtp/mkesmtpdcert.in.orig	2021-05-23 14:00:04.926537000 +0200
+++ courier/module.esmtp/mkesmtpdcert.in	2021-05-23 14:04:14.542517000 +0200
@@ -44,7 +44,7 @@
 then
 	cp /dev/null "$PEMFILE".pem
 	chmod 600 "$PEMFILE".pem
-	chown @mailuser@ "$PEMFILE".pem
+	/usr/sbin/chown @mailuser@ "$PEMFILE".pem
 	dd if=@RANDOMV@ of="$PEMFILE".rand count=1 2>/dev/null
 	@OPENSSL@ req -new -x509 -days 365 -nodes \
 		  -config @sysconfdir@/esmtpd.cnf -out "$PEMFILE".pem -keyout "$PEMFILE".pem || cleanup
@@ -74,7 +74,7 @@
 
 	cp /dev/null "$PEMFILE".pem
 	chmod 600 "$PEMFILE".pem
-	chown @mailuser@ "$PEMFILE".pem
+	/usr/sbin/chown @mailuser@ "$PEMFILE".pem
 	cat "$PEMFILE".key "$PEMFILE".cert >"$PEMFILE".pem
 	rm -f "$PEMFILE".key "$PEMFILE".cert
 fi