Critical Path’s servers on May First/People Link uses a technique called greylisting to help reduce the amount of spam being sent to our servers. Greylisting means that the first time an email message is sent to our server, our server defers delivery – telling the sending mail server: “Try again later.” The next time the sending server tries to send the message, our server accepts it.
Once an email sender/recipient combination has been greylisted once, it will not be greylisted again. So – this step will only happen the first time a sender sends you a message.
Why is this useful?
Legitimate email servers will resend their message in around 30 minutes. Most spammers do not run legitimate email servers, and so never retry their spam messages. This greatly reduces the amount of spam that MF/PL’s mail servers need to handle, and means that we can devote a greater proportion of our resources to handling your legitimate mail.