What is “greylisting”?

Greylisting is a security measure that may be use against spam and spammers. The mailserver who does greylisting will momentarily block email from any sender that’s not part of its greylist database.

If the message is a legitimate one, the server that sent the mail will, after a slight pause, attempt to send it again. This is a default behavior with email transportation protocols.

If the message ist sent again by the sending server after some time, the receiving server has it’s data in its greylist database and will accept the mail.

The message will be sligthly delayed, bust the spam risk is reduced, because most spammers do not resend mails that got rejected first.

How does Mailix use greylisting?

Mailix does not do greylistung by default. So your regular, good email message won’t be delayed.

Hoever, if our systems detect several signs of possible spam at a message sent to us, we may sometimes temporarily reject such messages to check if they are sent again. Such messages will be successfully received at the second attempt to send, just like with greylisting. So greylisting is a situation related measure at Mailix.

If we handle a message with greylisting, we make sure that a second attempt so send it to us will be successfull, even if the message is sent from another mailserver by the sending provider.