A guide to Global Whitelist in
Pegasus Mail and Mercury/32.

This document is last updated 17-July-2006.



Why does this page only refers to Pegasus Mail?

Mercury/32 version 4.1 and Pegasus Mail version 4.41 share the same mechanism for using Pegsus Mail's Global Whitelist. Mercury/32 will look for the file white-m.pm in the users home mailbox location and when the senders address is in that list will take no further anti-spam actions on the message.

Just for the record: Mercury/NLM (for Novell) does not have this feature.

General Global Whitelist information

Pegasus Mail provides extensive filtering capabilities, aimed mainly at dealing with spam, or unwanted commercial mail. Unfortunately, there is no anti-spam technique that can guarantee it will provide 100% accuracy in discriminating between spam and not-spam messages - inevitably, at some point, a spam filter is going to classify a message as spam when it is not. When this happens, the mis-classified message is known as a false positive. False positives can have very serious implications - imagine, for a moment, that a very large order comes in but is incorrectly classified as spam: if you don't happen to scan your folder in time, you may lose the order.

Because the consequences of having false positives are so serious, Pegasus Mail provides a mechanism to help reduce them - it allows you to create a Whitelist of addresses from which all mail is to be assumed to be not-spam. When Pegasus Mail finds a message from a sender whose address appears in your whitelist, it will not pass the message to either Spamhalter or to Content Control, but will mark it as whitelisted instead and leave it in your new mail folder. Note that whitelisting does not prevent a message from being processed by your New Mail Filtering Rules, although a rule test exists that allows you to detect whether or not a message has been whitelisted in your rulesets (this test is an attribute test and can be created by clicking the "Attribute" button in the filtering rule editor window).

You can manage your whitelist by selecting the Whitelist... option from the Spam and content control submenu of the Tools menu in Pegasus Mail. This will open the Whitelist management dialog, where you can add and remove addresses, and control the behaviour of the whitelist.

Your current whitelist appears in the list control at the top of the dialog. Because the list can contain many hundreds of addresses, a Find... button allows you to do an incremental search through the list: this means that you can enter a few characters from anywhere in the address you want to find, and the search code will automatically find the first occurrence of those characters in the address list. To skip past that occurrence and find the next match in the list, click the Next button, or alternatively, type in a few more characters that narrow down the search even further.

You can manually add addresses to your whitelist using the Add button. Similarly, you can remove addresses using the Delete button, and change existing entries using the Change button.

Maximum number of entries in whitelist
The whitelist is maintained in memory while Pegasus Mail is running, which means that it's very fast, at the expense of occupying some of your system RAM. You can control the number of entries Pegasus Mail will store in your whitelist using this control, but spend a moment considering how many entries you really need before altering the default value. Generally speaking, a number between 500 and 1000 represents a good compromise between storage and speed. Setting a very large number (for instance, 40,000) may slow the sending and receiving of mail and cause Pegasus Mail to use more system RAM. Whenever there are more addresses in the list than the limit you specify, the addresses at the bottom of the list (which are usually the least-frequently-used) are "dropped off".

Setting the number of entries to zero
As a special case, if you set the maximum number of entries in the whitelist to zero, you will effectively disable the whitelist without clearing it: Pegasus Mail will not check your whitelist, nor will it automatically add addresses to it, but any existing addresses in the list will be retained. This is handy in occasional cases where you want to disable whitelisting for a while then return to it later.

Automatically whitelist any address to which I send mail
When this control is checked (the default) Pegasus Mail will automatically add the address of anyone to whom you send a message to the top of your whitelist. If the address already exists in the whitelist, it will be automatically moved to the top of the list. This means that addresses to which you send mail frequently will tend to cluster at the top of the whitelist, while less-frequent and one-time addresses will eventually "fall off the bottom" of the list. It is worth being aware that if you use distribution lists regularly, every address in your distribution list will be whitelisted if this control is enabled.

Make this whitelist visible for Mercury/32 to use
If you use Pegasus Mail's companion mail server, Mercury/32, you can share your whitelist with Mercury/32 v4.1 and later. This tells Mercury/32 not to apply anti-spam processing and other tests to any address it finds in your whitelist when it is attempting to deliver a message to you (it does not apply to any other users). If you would prefer that Mercury/32 did not use your whitelist, simply uncheck this control and the whitelist will apply only to Pegasus Mail itself.

Specialized address forms
There are certain specialized addresses you can place in your whitelist that Pegasus Mail will handle in specific ways.

Domain-only addresses
If you enter an address containing no '@' symbol, Pegasus Mail will interpret that as an e-mail domain from which any mail should be accepted. So, if you want to accept mail from any user in the domain pmail.gen.nz as whitelisted, simply add an entry containing only the string pmail.gen.nz.

Regular expressions
If you enter an address containing an asterisk (*) or a question mark (?), Pegasus Mail will treat that as a limited regular expression and process it accordingly. The '*' character represents any number of characters, while the '?' character represents any single character. So, for example, if you want to accept mail from any user at the domain pmail.gen.nz whose username starts with the letter 'D', you would add this expression as an address:

d*@pmail.gen.nz

You can only add specialized address forms of this kind using the Add button in this dialog - Pegasus Mail will never add them automatically.

 

 


If you have more information that should be placed on this Global Whitelist page, please feel free to contact me by e-mail and I will make that information available.
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