Update mx_check.conf

data/conf/rspamd/local.d/mx_check.conf

@@ -1,4 +1,4 @@
-timeout = 1.0;
+timeout = 8.0;
 symbol_bad_mx = "MX_INVALID";
 symbol_no_mx = "MX_MISSING";
 symbol_good_mx = "MX_GOOD";