What is greylisting?

Answer 1

Greylisting is an email filtering technique used to combat spam. When a mail server receives a message from an unknown sender, it temporarily rejects the email and asks the sender's server to try resending it after a certain period. Legitimate servers will typically retry sending the email, while many spam servers will not, effectively reducing the amount of spam that reaches the inbox. This method relies on the behavior of email servers to differentiate between genuine and spam messages.