Is your inbox constantly filled with spam? Research shows that up to 90 percent of all emails are spam. They aren’t legitimate messages. Rather, they are unsolicited advertisements or phishing schemes. While you can always use a blacklist to prevent spam from cluttering your inbox, you may want to use a greylist, instead. Greylisting works in a similar way as blacklisting, but it’s not as invasive.

What Is Greylisting?

Greylisting is a form of spam filtering that involves temporarily blocking emails sent from Internet Protocol (IP) addresses that aren’t part of a database. Most spam emails aren’t sent multiple times to the same recipient. Spamming is a number-based game. A spammer may send a spam email to thousands of recipients. If a recipient’s server rejects the spam email, he or she typically won’t resend it. With greylisting, these spam emails won’t clutter your inbox.

With greylisting, unless an email is sent from an IP address that’s part of a database, it will be temporarily blocked. Your inbox will only accept them if the sender attempts to resend them. Most spammers won’t take the time to resend emails if they are blocked during the initial delivery. As a result, greylisting can protect against spam emails.

Greylisting vs Blacklisting: What’s the Difference?

There’s also blacklisting, which is another form of spam filtering. Greylisting and blacklisting, however, aren’t the same. Blacklisting is designed to block all emails sent from a particular IP address. Whether the sender attempts to send an email a single time or a dozen times, your inbox will reject it. Blacklisting involves a list of banned or blocked IP addresses.

Greylisting falls somewhere between whitelisting and blacklisting. It doesn’t involve permanently blocking emails from a given IP address, nor does it involve accepting all emails from a given IP address. Rather, greylisting will temporarily block all emails that aren’t part of a database. The database is essentially a whitelist. It’s a list of all legitimate and verified IP addresses. If a sender isn’t part of the whitelist, his or her initial email will be temporarily blocked. The sender can then resend the email so that it reaches your inbox.

In Conclusion

There are different ways to block spam emails. Regardless of which email service you use, it probably has spam filtering technologies in place. With that said, you may want to look into greylisting as well. Greylisting is an alternative to blacklisting. It’s designed to temporarily block all emails sent from unknown or unverified IP addresses.