Email Blacklists

  A sledgehammer approach to the Spam problem

Spam or unsolicited email is an ongoing problem for Internet users.  However, there is one solution to the problem which causes much grief to ordinary and innocent users.  These are the various ant-spam blacklists used by many ISPs and other organisations or businesses who run mail-servers.

Innocent Users

The majority of these blacklists are based on the IP addresses of senders and frequently this can result in innocent users being included on the list. 

To explain in more detail (this is the techie bit)

Every device connected to the Internet, router/modem/web-server etc., needs a unique IP address to communicate. This address consists of 4 numbers such as Major users such as large businesses have a static IP address which doesn’t change. However, most home users and small businesses will have dynamic addresses which are changed /re-issued each time they log on, or restart their router. ISPs such as Virgin and BT have a range of IP address which they issue.

Collateral Damage

Let us say that there is a customer X of an Internet Provider and their PC has been compromised by malicious software (such as botnet) which is causing it to send out span.  This customer logs off after a session and that IP address becomes available to another user, In the meantime, that IP address has been has been included one of these blacklist databases as a span source, and hence when customer Y logs on they are allocated that blacklisted IP address without knowing that it is on a blacklist. They have become ‘collateral damage’ in the anti-span wars.  On the other hand the offending PC will still be compromised and sending out spam a couple of days later from a fresh IP address!

Of late some blacklists have taken to including all the IP addresses of an internet service provider if it decides that too many of them are on their blacklist.  The level to trigger this can be a low as 2%!

Another reason that I am finding people’s IP address appearing on blacklists is because their email account is not configured quite correctly in their computers.  The blacklists claim that they are not following the protocols as laid down by their Internet service provider such as BT.  But the ISP is allowing the emails out via their connection.  Surely it is up to the ISP, to whom the users concerned are subscribing to police these matters; not some foreign based unaccountable body.

Blacklisted users will find that some (maybe most) emails which they send get through if the receiving mailserver doesn’t use that particular blacklist service, but some may not.  Depending on how the receiving mail server handles it, one of three things may happen.

  • The email is forwarded but marked as ‘Spam’
  • The email is bounced back to the sender – in which case the sender knows it has failed to get through, but won’t understand why.
  • Worst of all, it may just be binned, in which case the sender knows it was sent, but the recipient claims it never arrived.

You discover whether their IP has been blacklisted by using one of the several blacklist monitoring services lists below.  These will automatically* discover your IP address and then allow you to run a check.

Even if you appear ‘clean’ you will be surprised at the number of blacklists which are being operated.

Sledge-hammer Approach

To my mind, these blacklists are a sledge-hammer approach to the problem unsolicited email, which demands a more targeted solution.  These “self-appointed guardians of the Internet” are disrupting the communications of innocent people.  It is possible to submit a request via the web to be removed from a particular blacklist (if you know that you are on it in the first place).  However with some blacklists they seem to assume that one is a large corporation with your own domain name and a static IP associated with that, so removal is almost impossible.  The vast majority of email users don’t even know what an IP addresses is, never mind that it (they) might be blacklisted.

Even if you can get your IP address de-listed from one blacklist, there are about 99 more to deal with!

 *If it doesn’t automatically discover your IP address, you can find it yourself by going to the website: – you IP addresses will be displayed near the top of the page as a group of 4 numbers.  Make a note of it; or copy and paste:

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