What they are:
A blackhole list, sometimes simply referred to as a blacklist, is the
publication of a group of ISP addresses known to be sources of spam, a
type of e-mail more formally known as unsolicited commercial e-mail . The
goal of a blackhole list is to provide a list of IP addresses that an ISP
can use to filter out undesireable traffic.
How it works:
An email is addressed to one of our users. The email then is checked to
see what IP address sent it. If the IP address is on the blacklist, then
it is returned to the sender.
Why this is a good idea:
This will help encourage the administrators of various ISPs to keep an eye on their users and close any accounts that are sending spam
and close their open relay servers.
Using a spamlist also reduces the workload of the mailserver which is busy
processing valid emails. So far it looks like using blacklists is reducing
the server load by 40-50%.
Error Message:
"The following message could not be delivered to
user@humboldt1.com. At host humboldt1.com 206.13.45.1. Because sender's
address was rejected. 553 5.3.0 message from <some IP address> rejected-see
http//njabl.org."
How to determine what the problem is:
Go to http://njabl.org/lookup.html and type in the <some IP address> of the server
from the error message. They will explain why that ISP is on their list.
How One gets on the list:
There are only 3 ways for IP addresses to get listed in the njabl.org dnsbl.
1. Operating an open relay
2. Being a dial-up port IP address
3. Operating a system that directly sends out spam (unsolicited, bulk email, usually of a commercial nature)
How to remove themselves from the list:
Have the administrator of the sending ISP go to
http://njabl.org, fix the problem and remove themselves from their list.