Greylisting                                                                         

Greylisting is a technique used to battle spam. The idea is very simple and yet very effective against spam. Most spamming is done by drone like email senders. Usually in the form of an infected machine. In it's rush to get the mail out, these emailers typically will not wait if our server tells them it's busy. A normal email server on the internet anheres to a set of standards. One of which says if a server is busy when trying to deliver mail to it, you should return in a few minutes and try again.

Most spammers program their senders to move on to the next server. So greylisting basically means we tell everyone who connects to us for the first time that we are busy and to come back in 40 seconds. When a real server with legitimate email contacts the second time, we take the email. If a server has not talked to us in 30 days, we consider it a new server and it gets greylisted again. The amount of time the server will wait to reattempt delivery varies from server to server, but most will try again in just a few minutes. But greylisting does have the effect of slowing incoming mail down. This delay is usually measured in minutes. Email delivery times are always varying as the internet experiences different levels of traffic.

Currently, greylisting has another side issue as well. It will also greylist you when you send mail. Your Outlook will report a server disconnect error. Don;t worry about this, it's just our server telling Outlook to come back in a few minutes. You will notice the email you tried to send is in the outbox. You will also notice the email automatically resends it self shorlty. We are working with Merak Mailserver to find an answer to this problem.

Greylisting should not block any emails that are from legitimate servers. Remember, this method does not judge or block the email or do any routing based on the email itself, it simply delays the the receiving of the email. In our test implementation, we have seen significant reduction of incoming spam. We will monitor our server closely to see what effects it has on real time traffic. Please don't hesitate to contact us with any questions or issues you have.