How SPAM Blacklists Work
We have all heard of SPAM Black Lists, but do you know how they work?
On the surface, they are designed to maintain a list of IP addresses and domains that are associated with known spammers. They are used by email service providers to filter incoming emails, blocking any messages originating from those listed IP / addresses, preventing spam from reaching users’ inboxes.
There are over 300 known email blacklists that anyone can access, and hundreds of private lists. Some companies maintain their list, while others buy subscriptions to list and others purchase application servers such as the Barracuda email blacklist application server by Barracuda Networks, Inc.
Stopping SPAM is a big business, but sending SPAM seems to be an even larger business.
It is obvious that people still fall for scams via email; otherwise, spam wouldn’t be such a big business. It is estimated that more than $200 million a year is made by peddlers of spam. It is estimated that 162 billion spam emails are sent every day in 2024, that is, every day, not annually. And sadly, the two biggest spam-sending countries are China and the US.
Stopping this is where SPAM Blacklists come into play. When SPAM is detected either automatically by scanning applications or manually by someone hitting the report as SPAM button, the offending email servers are added to blacklists (once a threshold has been reached). Using Gmail as an example, Google states that if a senders spam rate reaches 0.3% they could risk getting reported as SPAM and face delivery restrictions or a complete block.
It Is Easy To Get Blocked and Difficult To Get Unblocked
Based off of the Gmail policy, if you are a small business and you send out a email to 100 clients (who all opted-in to receive your mailings) and just one or two of them report you as SPAM, you could get blacklisted. And once you have been blacklisted it can take hours, days and even weeks to get unlisted. And depending on what blacklist(s) you are on, it also can take a fine or fee to be paid.