Hi,
We're using the require_resolvable_fromhost plugin, and have seen that
there is a bug in it. MAIL FROM commands with legitimate domains where
getting rejected as not resolvable.
The bug has been tracked down to domains that have zone files with
unresolvable MX records.
example.com. 3600 IN MX 10 fakeserver.example.com.
example.com. 3600 IN MX 20 mail.example.com.
example.com. 3600 IN MX 30 anotherfakeserver.example.com.
The plugin tries to resolve every MX record in the list (to see if it
has an A record), but gives up on the first unresolvable one,
considering the whole domain unresolvable.
I consider this a bug, as leaving fake MX records is a known antispam
technique, and after all, the domain is resolvable if you have at least
one resolvable MX record.
Patch attached:
Index: plugins/require_resolvable_fromhost
===================================================================
--- plugins/require_resolvable_fromhost (revision 1)
+++ plugins/require_resolvable_fromhost (working copy)
@@ -53,8 +53,14 @@
$res->udp_timeout(30);
my @mx = mx($res, $host);
foreach my $mx (@mx) {
- return mx_valid($self, $mx->exchange, $host);
+ # if any MX is valid, then we consider the domain
+ # resolvable
+ return 1 if mx_valid($self, $mx->exchange, $host);
}
+ # if there are MX records, and we got here,
+ # then none of them are valid
+ return 0 if (@mx > 0);
+
my $query = $res->search($host);
if ($query) {
foreach my $rrA ($query->answer) {
Jose Luis Martinez
[EMAIL PROTECTED]
CAPSiDE
