Re: Blocked ip by spam

From: Michael Pelletier (mjpelletier_at_mjpelletier.com)
Date: 05/12/05 

Date: Thu, 12 May 2005 13:08:46 -0700

Javier wrote:

> Michael Pelletier wrote:
>> If he was blacklisted by a DNSBL then the spam email would have been
>> blacklisted by the SPAM senders IP address not the "from" address. If
>> someone has blacklisted him on their smtp gateway(s) then you are correct
>> they probably blocked his email address even when it was not technically
>> sent by him (spoofed). Their are a lot of dumbass email "administrators"
>> that block by email address even when it was spoofed ;-(
>>
>
> How could I know if my server was spoofed ? Do you a tool to make a test ?

How did you know you were blacklisted? Did you get a failure message? The
first thing you need to find out is how you were blacklisted. Was it by a
DNSBL or was it local (ie an email admin blocked you on his/her email
gateway). The best way is to look at the failure message. I send failure
messages that will "point" you to the DNSBL you are listed on. If you do
not know, email me your information and tonight I will do some searching
for you. You need to email me your doamin name...my email address above is
my personal email system and it is real. Also send me your failure email
message.

>> I would recommend using procmail or sendmail (latest version) on a non
>> windows box for your email gateways. This allows you to use anti-SPAM
>> applications like Razor, Spamassasin, MIMEDefang (not only is it good at
>> filtering bad mime emails but also is very good at filtering/sanitizing
>> html email by the way) and DNSBL (you can use DNSBL with windose too).
>>
>
>
> Thanks for your recommendations, but I run windows.

No time better than the present to learn some Linux/*BSD...I would highly
recommend *NOT* using exchange as your email gateway...

> Nevertheless, I wonder if those tools are for pop servers or they check
> smtp out traffic...

Not sure what you mean by that statement. If you are asking who DNSBLs work,
the email gateway, upon receiving and email, will check the IP address of
the client sending the email against the DNSBL. If it receives a "special"
reply then it knows to block/reject the email. Please realize that my
description above is very generic. If you do a search on google you can
find more specific information about DNSBL and how they work.

To answer your question above, DNSBLs do not work on POP/IMAP servers. POP
and IMAP are the protocol that a typical email client uses for
sending/receiving email from it's server. SMTP is use to send email from
*YOUR* email server/gateway to someone else's *SERVER*. That is where the
DNSBLs are used...

> Thanks
>
> J

Again, realize that doing a google search and spending some time reading is
probably better than my 2 minute description...

Michael 

-- 
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http://www.gnu.org/philosophy/can-you-trust.html
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Relevant Pages

  • Real IP to internal SMTP and not 127.0.0.1
    ... I tried to use a DNSBL filter (Symantec Mail ... the SMTP but in the FTP log I found this problem. ... If I delete the SMTP server publishing, and set the SMTP to listen on the ...
    (microsoft.public.isa.enterprise)
  • Re: content filtering
    ... While that's an admirable goal (refer to Bill Gates saying that spam ... If you want to consider the presence of an IP address in a DNSBL ... If a server is set up properly and message bounced with a SMTP ... 550 code would come to the attention of the mail server admin who could ...
    (microsoft.public.exchange.admin)
  • Re: Filtering
    ... basic spam filtering is now included within SBS2003. ... If the IP address of the server which is sending the ... > don't use the DNSBL within Exchange, I actually use it within the Symantec ... The SPAM filtering will not work if you download emails ...
    (microsoft.public.windows.server.sbs)
  • Re: using RBLs interactively
    ... use the query form at spamhouse.org, ... $ nslookup -type=txt 1.0.0.127.zen.spamhouse.org ... Server: eagle.xile.realm ... The txt record for a DNSbl entry should be included verbatim with the reject code, because it has important information should a real message be classified as spam. ...
    (comp.os.vms)
  • DNSBL exclude mail from certian email addresses
    ... find in the sendmail documentation or elsewhere. ... server to send and receive mail for business purposes. ... Everything I've found explains how not to run dnsbl checks if the mail ... But, for instance, one of our smaller customers uses a ISP ...
    (comp.mail.sendmail)
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