On this server, mails will be checked by a greylist. This page shows the current status of this greylist for the last 24 hours. The statistic only contains the absolute number of registered senders, not the number of delivery attempts, so the values will not be falsified by regular and desirable mail contacts.

Greylisting is a method to fight spam. Senders, who send a mail for the first time, will be temporary blocked and stored in the greylist. Regular mail servers will attempt to deliver the mail a second time after a while, as it is not unusual, that mails can not be delivered immediately. At this second delivery attempt, the sender is known and the mail will be delivered. Further mails from the same sender will be delivered without any delay for a certain time span.

Spammers will send mails only once, as they often use just a simple SMTP client without any error handling. Even if some spammers use regular mail servers, there is a good chance, that the spammer is already known at the second delivery attempt and will be recognized by RBLs and spam filters.