Greylisting in cPanel is a great idea in theory. The idea is that when a mail server connects to your mail server, your mail server will temporarily refuse the connection expecting any legitimate server to try again at a later time. This, in theory, would stop spam emails from being received. Spammers usually try to send emails just once in bulk.
The problem with Greylisting is lots of companies now ask you to authorize login attempts via email. This usually means waiting for a code to enter on the provider’s site. With Greylisting emails that email you are waiting for is deferred.
Here is a prime example. Disney released its new streaming service Disney+ and to gain access to the Disney control panel you have to enter the code that is sent to you. Great, but the code is only valid for 10 minutes. Meaning if you use Greylisting you won’t be able to access your account.
Another example is Coinbase.com. If you horde Crypto, buy or sell and you attempt to log in to Coinbase.com then you will likely have to wait for the authorization email. Coinbase.com only send this email once. If your mail server defers the connection then you won’t be able to authorize your login.
In theory, Greylisting in cPanel / WHM is a good idea but in practice it’s flawed. Instead, you can use SpamAssasign with a higher block rate. This way you can filter out suspected spam and have that delivered to a spam folder for review at a later time.
For an even harsher way to combat spam, you can use Boxtrapper where you or the sender have to authorize every email. Eventually, you gain a large whitelist where emails flow freely from people you have spoken to before.
How To Disable Greylisting In WHM.
Greylisting can be disabled in WHM. Log in as the root user and in the search bar type “Greylisting” on that page slide the bar to the left to disable Greylisting.
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