diff -urNp syslog-ng-3.32.1-orig/configure.ac syslog-ng-3.32.1-dwok/configure.ac
--- syslog-ng-3.32.1-orig/configure.ac	2021-06-26 17:44:31.429714832 +0200
+++ syslog-ng-3.32.1-dwok/configure.ac	2021-06-26 17:45:07.694307333 +0200
@@ -1278,7 +1278,7 @@ if test "x$enable_smtp" != "xno" && test
 		CPPFLAGS="$CPPFLAGS_SAVE"
 		LDFLAGS="$LDFLAGS_SAVE"
 	else
-		PKG_CHECK_MODULES(libesmtp, libesmtp-1.0)
+		PKG_CHECK_MODULES(LIBESMTP, libesmtp-1.0)
 	fi
 	enable_smtp="yes"
 fi