Realtime Black List - RBL - Yaritz Consulting: The Consultation Company  

You have made it to the RBL page.

RBLs (Realtime Black Lists)

You are here because you might have previously attempted to send email and received a bounce email, or are looking to stop UCE (Unsolicited Commercial Email, formerly known as spam).  To curb UCE, most companies are running a realtime black list.  RBLs usually block about 75% of UCE, because they block IP addresses used to send UCE.  RBLs are intented to only block repeat UCE offenders using the same IP address.  When a sender of UCE changes their IP address, the RBL will become useless.  As with all RBLs, there is a high chance of blocking legitimate email because senders of UCE try to use legitimate IP addresses to get their so-called advertising out.  This can irritate folks who use dynamic IP addressing, which in most part will be blocked.

The creation of a RBL is easy and simple and can be created as follows.  The real problem with a RBL is keeping it up todate.  Most senders of UCE move along by the time the list takes on its most profitable use.  This is why and others have dropped the length from two weeks to just a few days.  There are a few RBLs that will keep an IP entry on the list longer if it keeps attempting to send UCE.

The creation of a RBL is easy.  Just follow these steps:

  1. Setup a DNS server of your choice
  2. We will use a reverse annotated IP entry (localhost will look like
  3. Create an A record pointing to a local IP.  I usually pick
  4. Create a TXT record with the proper explanation. (This will be sent back to the sending MTA and relayed to an inbox.  A good idea is to include a weblink or some other contact method for legitimate emailers.  Most UCE offenders ignore this entry and move on.)
  5. Point your email server at your RBL domain and test away.

The main problem with RBLs is that using such a list give is that they give someone else control over the email you can receive.  This can also be an excellent solution as the blocking happens on a per IP basis.  Once a sender of UCE is found, everyone can block those message, but remember to unblock once they stop.

More information

For Consulting information and other questions, click here