Hi Paolo,

Everybody's opinion of what to use is different but if you would like to
follow what I have done:

reject-empty-rdns ... Definitely use this
reject-missing-sender-mx ... Definitely use this
reject-unresolvable-rdns ... Hmm...You will get some false positives if you
use this but *personally* I find it solves more problems than it creates. I
would probably not enable it on "mainstream" servers, but would enable it on
"anti-spam hardened" servers.
reject-ip-in-cc-rdns ... I do not use this personally as it would cause too
many false positives for me.


I do not use rhsbl's purely because I have not found a good comparison list.
Does anybody have any suggestions?

With normal RBLs, I always use zen.spamhaus.org and bogons on "mainstream"
servers, and add sorbs and spamcop and maybe a few others to "anti-spam
hardened" servers.

By "anti-spam hardened" servers, I mean servers whose email users are
willing to put up with some false positives in exchange for very little spam
getting through. And by "mainstream" servers, I mean ones where the users
need to put up with a higher level of spam getting through in order to make
sure there are no, or at least almost no false positives. A typical hosting
server with a large proportion of business customers, for example.

This is nothing to do with spamdyke but similarly I would use spamassassin
drop/delete scores of 14 on "mainstream" servers, and 8 on "anti-spam
hardened" servers. If you have ever played with your spamassassin settings,
maybe these values will give you an indication of the difference in how
strict these two "types" of installation might be.

VITAL: On a busy mainstream server, I always use the policy-url option,
linking to a page that explains what is going on and what to do about it,
and who to contact for help. If a legitimate sender gets blocked, and they
are able to read an error message, they will know what it happening and how
to resolve it. 

SAM: To go on the wishlist, please can you add an option where the policy
URL can have the block reason appended in some way (e.g.
www.domain.com/policyurl.php?error=WHATEVER, so that we can point people
directly to the info they need rather than making them match their error
with a list on our policy url page?


Remember, these are just what *I* use on our servers. I think they are
optimal. Others will completely disagree. It is down to personal preference.
The best option is to keep an eye on your logs to see how much spam they
block, and try to spot any false positives. Personally I'm very sad and
absolutely love and enjoy watching at maillogs in real time, seeing all the
moronic spammers (and most often compromised consumer PCs if the rDNS is
anything to go by) get blocked.


Faris.

* The Asterisk (Voip) mailing list server has no rDNS. I can't believe it. I
had to whitelist it. It is one of the busiest mailing lists I belong to. The
people who run the mailing list are serious experts in the VoiP arena and
know their coding inside out, yet their mailserver has no rDNS. I did
politely email them to let them know, but I've not heard back :-) Anyway, it
does show how legitimate senders do sometimes have no rDNS, and how you will
sometimes have to whitelist.


> 
> Paolo wrote:
> > Hello everybody,
> >
> > I hope this is not a FAQ , I'd like to know if there is some reason
> to
> > prefer rbl to rhsbl .
> >
> > Wouldn't it be nice to write down a list of options  with explained
> how
> > much is the risk of rejecting good mail ?
> >
> > for example in my configuration I've not enabled these options and
> would
> > like to know if they could generate many false positive:
> >
> > reject-empty-rdns
> > reject-missing-sender-mx
> > reject-unresolvable-rdns
> > reject-ip-in-cc-rdns
> >
> >
> > Maybe it could be useful to make a survey of people's enabled options
> > and most used rbl ?
> >
> > Thank you
> > Ciao
> > Paolo
> >


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