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From: Dennis Peterson on 12 Jan 2007 11:37
Marek Pedziwiatr wrote:
>> Which DNSBL do you use to block spam at your site?
>> [As a rule of thumb I would suggest maximum 3 from non local source]
>>
>
> In sendmail I use dnsbl features:
> FEATURE(`dnsbl', `proxies.blackholes.easynet.nl', `"550 5.7.1 ACCESS DENIED
> to OPEN PROXY SERVER "$&{client_name}" by easynet.nl DNSBL
> (http://proxies.blackholes.easynet.nl/errors.html)"', `')dnl
> FEATURE(`dnsbl', `relays.ordb.org', `"550 Email rejected due to sending
> server misconfiguration - see http://www.ordb.org/faq/\#why_rejected"')dnl
> FEATURE(`dnsbl', `bl.spamcop.net', `"450 Mail from " $`'&{client_addr} "
> refused - see http://spamcop.net/bl.shtml Twoj serwer jest na czarnej liscie
> SpamCop."')
> FEATURE(`dnsbl',`sbl.spamhaus.org',`Rejected - see http://spamhaus.org/')dnl
> FEATURE(masquerade_envelope)
> FEATURE(`dnsbl')
> FEATURE(dnsbl,`blackholes.mail-abuse.org',` Mail from $&{client_addr}
> rejected; see http://mail-abuse.org/cgi-bin/lookup?$& {client_addr}')dnl
> FEATURE(dnsbl,`relays.mail-abuse.org',` Mail from $&{client_addr} rejected;
> see http://work-rss.mail-abuse.org/cgi-bin/nph-rss?$& {client_addr}')dnl
> FEATURE(dnsbl,`dialups.mail-abuse.org',` Mail from dial-up rejected; see
> http://mail-abuse.org/dul/enduser.htm')dnl
> FEATURE(`greet_pause',3000)dnl
>
> Additionaly I use RBL included in spamassassin + DCC + SPF
>
>

ordb.org is gone - they shut down their operations. mail-abuse.org is
now Trend Micro and it's worth a look to see if they've changed their
access rules. In particular look for combination lists so you need make
just one call to their servers. You might also wish to test response
times for each service and place the faster servers at the top of the list.

dp
From: NPG on 13 Jan 2007 14:04
* J�rn Dahl-Stamnes wrote:
> Marek Pedziwiatr wrote:
>
>> FEATURE(`dnsbl',`sbl.spamhaus.org',`Rejected - see
>> http://spamhaus.org/')dnl FEATURE(masquerade_envelope)
>
> spamhaus.org: Unknown host
spamhaus.org is operational. http://www.spamhaus.org
So don't believe everything this guy says.

Check all your DNSBLs and consolidate when possible.
From: jmaimon on 14 Jan 2007 20:45

Marek Pedziwiatr wrote:
> Hello
> I use sendmail 8.13-7.
> I've got a problem to send emails from my server to some smtp servers based
> on Exim
> From time to time I can see:
> "Deferred: 451 Could not complete sender verify callout"

Doesnt sound like a stock sendmail error message

> in maillog during connection to some servers.
> I can't find out if it's my sendmail misconfigurtion problem or problem is
> on other sites.
> Some times it helps if I add
> Connect:a.b.c.d OK
> line in /etc/mail/access , but I don't like this method.
> Do you have any suggestion how to solve this question ???

Check with the other sites to find out exactly what it is that they are
doing that might be impacting you.

Sure sounds like they are doing verification checks on you which means
that they connect back and pretend to attempt to send email to the
alleged sender of your message, which could be failing to complete in a
timely manner due to strict timeouts on their side and unneccessary
delays on yours.

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