There are many things that have made cPanel the most commonly utilized control panel system all around the globe. One of these is the continuous improvements the developers make in order to allow users to enjoy a much safer, more convenient web-based experience.
The addition of a new feature called “Greylisting,” is one of the latest proofs that the brains behind cPanel and WHM want to make things better for all its users. This feature is something you should be excited about, as it will dramatically minimize the number of spam mails you, together with your customers, receive.
What is this Greylisting all about?
Basically, Greylisting is an email-deferring process applied to unknown senders. Whenever a new email arrives, this feature prompts the server to respond with a message that tells the sender to try sending the message again after some time. For Exim and other similar valid Mail Transfer Agents, retrial will be conducted numerous times. The time for retrying can range anywhere from a few minutes to several days. As for invalid MTAs, it is highly likely they will get tired of sending the email again and again.
How is Greylisting conducted?
Greylisting has been made possible by cPanel, thanks to its creation of its very own daemon, called “cpgrey.” The Greylisting daemon automatically starts at at SMTP receipt time. In other words, the process takes place prior to any information being sent.
Cpgrey works by searching for what is referred to as a “triplet.” This includes a source address for the IP, a source email for the email address, and a destination address for the IP. In the event that the combination is not detected within a customizable time frame, the daemon will then defer all the emails coming from the triplet for a specified, configurable block time. Once this time frame expires, the system will start accepting emails delivered by the triplet until expiration of the maximum block time occurs.
What are configurable in the Greylisting feature?
Another great reason to start taking advantage of Greylisting is simply because of its integration within the WHM interface. It has its very own interface in the system, which makes it easier for root users to tweak many of its different, useful components.
For instance, the initial block time can be customized, and so are the required retry time and triplet expire time. Furthermore, you can specify which emails can bypass the Greylisting procedure, as long as they come with valid SPF data. Additionally, the interface comes with a Trusted Hosts page, a feature that enables you to set which IP addresses and CIDR ranges are allowed to bypass Greylisting. Lastly, a simple report is also available, which provides you with the option to check current and existing triplets in your Greylist. Adding IP addresses and CIDR ranges can also be done from the report itself.
Where is Greylisting available?
The Greylisting feature can be accessed by cPanel users through both the X3 and the Paper Lantern interfaces. In a nutshell, you have control over which domains you want this feature on.
Greylisting is a powerful tool that you should use as soon as possible, so that you can further protect yourself and your other users from spam.