[Fix] Fix DMARC whitelist misconfiguration

conf/modules.d/whitelist.conf

@@ -39,7 +39,6 @@ whitelist {
             description = "Mail comes from the whitelisted domain and has valid SPF and DKIM policies";
         }
         "WHITELIST_DMARC" = {
-            valid_dkim = true;
             valid_dmarc = true;
             domains = "${CONFDIR}/dmarc_whitelist.inc";
             score = -7.0;