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Roller Network Help - Greylisting

Greylisting is a filtering method that leverages the normal retry behavior of an RFC compliant MTA. It is effective against messages sourced from hijacked systems, viruses, and "send once" mailers. Greylisting works by comparing the sender IP address, envelope sender and envelope recipient with configurable timing parameters.

Important: If you use a greylisting filter downstream from Roller Network please whitelist us to prevent unnecessary delays. Our services utilize an RFC compliant MTA that will always retry. A current list of our IP addresses and hostnames can be found on the resource access page.

By default the Greylisting filter is disabled.

Configuration

The basic greylisting options for the Roller Network Greylisting filter are:

Additional Options

There are several additional options that control how the greylisting filter handles the client/sender/recipient triplet. These options are:

Greylisting Data Table

The Greylisting Data Table provides a live view of the current triplets and their timing. It is hidden by default. To show or clear the table click on the "show table" link to reveal additional options. Using this table you can observe how the filter is behaving based on your settings and adjust them to suit your needs. However, there are some setting combinations you should not use, such as setting the delay time longer than the retry window or a low maximum retry setting. Individual triplets may also be removed using the table, including clearing the entire table.

All of the Roller Network SMTP servers operate with synchronized greylisting. A message greylisted on one is automatically seen by the others. This includes the "fail" counter as well, which means that clients that try to bypass the greylisting filter by rapidly connecting to multiple servers will cause the failure counter to increase. A server acting as a "woodpecker" will quickly find themselves blocked by the maximum retries setting.

The Greylisting filter is available on accounts with a service level of Personal or higher.

References

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