Greylisting is a fairly simple way to vietnam whatsapp number data
figure out whether the sender is respectable or not. Recipient mail servers don’t accept any of the incoming emails, telling the sending server to try re-sending their messages again within a certain time frame.
A legitimate email server will analyze such a message and try again as requested. Once it tries again, you receive the message to your inbox. However, a server sending spammy emails won’t try again, thus leaving the email out of your inbox.
When an email server gets a message from an unknown sender, it’s blocked by greylisting while the server’s IP address and sender and recipient addresses are cached. The sending server gets a block, which looks like a temporary 451 error.
How Does Email Greylisting Work?
When the message is resent, italy insurance forum 2025: a look at the future of the insurance industry
its IP and address information is discovered in the greylisting cache, and the message gets the green light to appear in the mailbox. The information stays in the cache for 24 hours. So senders who don’t send you emails frequently would have to go through the greylisting process again.
Each mail server sets a different time for the duration of which it requires the message to be resent. Usually, it’s between one and thirty minutes. The default value for most servers is 15 minutes. Even though greylisting delays the delivery speed of the email, it filters out the majority of spam messages, making your email experience much better.
If you are wondering how to stop spam email, greylisting is an excellent option.
Email Greylisting vs SPF
Greylisting and SPF are both lack data spam-fighting techniques. There is no need to choose between both options – they can be used together.
For example, some domains use several mail servers to send mail. Each mail server can be used for each next delivery attempt. In such a case, the greylisting process can be too time-consuming because each attempt from a new server will be greylisted separately.
This problem can be solved by using the Sender Policy Framework for such domains that make their SPF data available.
Greylisting is an efficient way to fight spam even though it comes with certain nuisances. By utilizing this tool together with other approaches, it’s possible to fight the majority of today’s spam.