A blacklist, as the name implies, is a list of people or
companies who have met with the disapproval of others. In the
online world a blacklist refers to those people who have been
marked as responsible for generating spam in a very big way.
Blacklists are also known as blocklists.
Blacklists are used to combat spam in a very specific way. When
spam is reported to one of the relevant spam fighting
organizations the IP address the spam originated from is added
to a banned or blacklisted IP addresslist. An IP address is the
unique location of you or your website on the Internet - think
of it as your "home address" online. To put it simply every
www.domain.com Internet address has a matching IP address. Any
email coming from your website domain also has a corresponding
IP address. If your IP address is present on a blacklist then
you're potentially wasting your time sending email to customers.
Why are you wasting your time? Modern spam blockers come with
the most common blacklists installed and/or allow you to import
updated blacklists into your spam blocker. This allows to you
block a huge amount of spam but you may also, potentially, block
legitimate email. Blacklists are not foolproof.
There are two types of IP address:
Dynamic - changes every time you connect to the Internet. Most
commonly used for dialup Internet access. Spammers love these
because they're very hard to track and 100% disposable.
Fixed/Static - All websites, most large companies and some
individuals use fixed IP addresses. This can cause huge problems
if they're reported for pamming.
When an IP address (dynamic or fixed ) is reported for sending
spam it's added to a blacklist. There are three different types
of blacklists:
Temporary An IP address placed on a temporary blacklist will
have email coming from that IP address blocked for several
hours. After a few hours the offending IP address is removed
from the blacklist.
Permanent When an IP address is added to a permanent blacklist
any email server configured to block email from this list will
never receive email from that range of IP addresses again.
Comprehensive This is the most damaging of blacklists. Not only
does it block a single IP address it also blocks the IP
addresses next to it. For example if the IP address
192.156.66.67 was added to a comprehensive blacklist then all IP
addresses close to 192.156.66.67 will also be blocked. This can
be a huge problem for those website owners using virtual hosting
because if your host has ever appeared on a blacklist then
you're also on the same blacklist, by default, because of the
shared hosting from the same IP range. It's important for all
website owners to check whether or not they're on a blacklist.
You'll need your IP address (available from your webhost) and
you can check your blacklist status at:
www.mail-abuse.org/cgi-bin/lookup
Blacklists are a necessary evil due to the volume of spam being
sent each day but are not an exact science. Take a few moments
from your day and ensure that your website or email address is
not being blocked.
About the author:
http://www.spam-site.com reviews and tests antispam software
solutions for the business and end user. Niall Roche is the
content author and owner of spam-site.com
