Recommended spam.lists and/or sendmail dnsbl settings?

Peter Farrow peter at farrows.org
Wed Dec 5 12:39:57 GMT 2007


Steve Freegard wrote:
> Duncan, Brian M. wrote:
>> I guess it is the case that everyone has different needs.
>
> Yup - most definitely.
>
>> We never reject messages at the MTA level. (Well actually messages that
>> are destined to users that do not have valid MS Exchange SMTP records
>> are rejected, so I guess never is not correct, but that is the only case
>> we reject at the edge)
>
> Count yourself very lucky then - I've worked with many companies in 
> the  past that had similar policies. They got so much junk they were 
> adding extra MailScanner servers or upgrading existing machines every 
> 6 months or so to attempt to keep up with the load that this imposed 
> on them.
>
>> RBL's tend to be a love/hate thing.  We love them, based on the fact
>> that we still deliver every failed RBL message to the users Junk Mail
>> folder. (Giving them the option to "white list" in outlook RBL'ed
>> sources.
>
> Yes - but in the case of Spamhaus (which is why people like them) if 
> you do some analysis you'll find that unless you've got horsepower, 
> disk space (and the associated money) to burn it isn't worth 
> delivering these messages.
>
> From the last SpamAssassin mass-check network tests run:
>
> xbl.spamhaus.org hit on 68.7% of spam messages and 0.0033% non-spam 
> messages (3 out of 90160 non-spam messages)
>
> pbl.spamhaus.org hit on 61% of spam messages and 0.43% non-spam (390 
> out of 90160 non-spam messages)
>
> sbl.spamhaus.org hit on 1.26% of spam message and 0.0388% non-spam (35 
> out of 90160 non-spam messages)
>
> Based on those stats - I love RBLs too as that tells me that I could 
> potentially gain 70% efficiency by rejecting them before they get to 
> MailScanner.
>
>> Given that Mailscanner allows "high scoring treatment" on RBL checked
>> messages, and then the capability to set the intended actions (including
>> delivery) I would think the extra control over RBL behavior could allow
>> even finer tuning in some environments.
>
> I agree - everyone has different requirements and I think checking the 
> Spam Lists in order and stopping at the first hit would make sense 
> from an efficiency point of view.
>
> Cheers,
> Steve.
For me,

If a sender/relay is listed on an RBL I reject it before it gets to 
MailScanner.  The sender knows they've been rejected so they can talk to 
their ISP or IT dept to fix the problem.   Personally I see no need to 
even consider email from somebody who relayed through a blacklisted 
server.  This has not caused any complaints from my clients.

Regards

Pete


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