Greylisting FAQ



 

What is greylisting?
Greylisting is a term used to describe a spam-blocking method.  Greylisting blocks spam at the mail server level, and is based on the behavior of the sending mail server rather than on the content of the message.

How does greylisting work?
Any new email message that is seen by the ECE mail server for the first time is temporarily rejected for delivery.  Sending mail servers that are properly configured will send the message again, typically within a short time.  When the second delivery attempt is made, the ECE mail system will accept the message and record in a database that this mail server is legitimate.  Any future email messages sent from this particular server will be delivered without delays for 21 days.

This procedure helps to prevent spam because spammer systems do not typically attempt to resend their spam after receiving a temporary rejection the first time. Therefore, by rejecting the first attempt at delivery, greylisting can help to reduce spam.

Does greylisting stop all spam?
No system can be 100 percent effective in stopping spam.  Implementation of greylisting has been proven to significantly reduce the amount of spam received.

Will greylisting block valid email messages?
Greylisting will eventually allow all mail servers that follow internet standards for resending messages to process normally.  However, some legitimate mail systems don't follow these standards. Identified legitimate sources of email can be added to an exception list.

Does greylisting replace spam or virus filtering?
No.  Greylisting is another level of protection against unwanted email, but it does not replace spam filtering or anti-virus scanning.

Will there be long delays in delivery of email to me?
Delays in email delivery will depend on the settings of the sending mail server.  Mail servers are configured to retry at specific intervals.  Most email messages will be delivered within a short time of the initial delay.

How does greylisting help me?
Greylisting should block a large percentage of spam.  You should see less spam in your inbox.  Most email that is processed by the ECE mail system is spam.  Greylisting will reduce the amount of unwanted email that comes into the ECE mail system and therefore should reduce the overall system load, thus improving performance.

Can I turn off greylisting?
No.  Greylisting is implemented at the mail server level.