"The Cybermagic
of Whitelists."
By Niall Roche
Before we start getting deep into the meat of
this article it's important to explain some standard terminology
to make sure the rest of this article makes sense.
*An IP address is a number which identifies your
location on the Internet.
*A blacklist is a list of IP addresses which
your antispam software uses to block incoming spam.
*A whitelist is the exact opposite of a blacklist.
A whitelist is a predefined list of IP addresses
that are allowed to send email to and receive email from each
other. Blacklists exclude known and suspected spammers. Whitelists
can be used to exclude everyone except known IP addresses.
Think of it like this. A whitelist is a like
having a phonebook which is owned by a small group of people who
only wish to speak directly to each other. They don't want just
anybody ringing them. Not only that but the entire group need
to approve new phone numbers before they appear in this exclusive
phonebook.
To send email to a whitelist you must be approved
by the owner of the whitelist. This is a lot like the double optin
systems used by legimiate ezines and mailing list owners. Whitelists
are the nightclub bouncers of the virtual world - if you ain't
on the list you ain't getting in. Simple but very effective.
A real world example of a whitelist would be
if two companies wanted to exchange email only with each other.
These companies could implement a whitelist that contained the
IP address for just the two email servers that want to send email
to each other. That would mean that any email coming from an IP
address not on the whitelist would be returned to sender. For
companies they can ensure that employees are only dealing with
work related email and not chatting with their friends.
The benefits of whitelists are many but proper
management of the whitelists is equally important. Misuse of whitelists
will only lead to more headaches for everyone involved with missing
email, irate customers and IT departments doing overtime just
being the tip of the iceberg.
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