Page 56 - Mercury Manual.book

51 Content Control
Editing a Content Control definition

apply these rules to any message that is not trapped by either the black or white lists. You can
either edit the rule file by clicking the Edit button next to the field, or by using an external
text editor. Unlike previous versions of Mercury, the internal editor now has no filesize lim-
itation - you can edit rule sets of any size using it.

Checking syntax When you are editing your rule file, you can check that the rules you have
entered are syntactically correct by clicking the Check Syntax button in the rule editor: if Mer-
cury encounters any errors in the rule set, it will pop up a dialog describing the error and place
the cursor on the line where the error occurred.

Weight at or above which this definition activates Within the rule file, each rule can be as-
signed a weight, which is a numeric value; after all rules have been processed, Mercury adds
together the weights assigned to every rule that matched the message - if the total weight is
greater than or equal to the value you enter here, the message will be deemed "unacceptable"
and will be subject to the action you define on the "Actions" page of the editor.

Check at most this many bytes in each message If you enter a value greater than zero here,
Mercury will only scan that many characters in each message when applying your content
control rule set. This can reduce the time taken to perform content control, but can also result
in less undesirable mail being detected. If you find that Content Control is taking a significant
amount of time on your system (for instance, if you receive many large messages), entering
a value of around 8000 in here will typically provide a good balance between speed and de-
tection.

Note that when scanning multipart messages, Mercury adds together the size of each text sec-
tion it scans to calculate the number of bytes it has scanned - it does not simply blindly read
through the file.

The Actions Page
On this page, you define what you want to happen to messages when they pass through the
content control system. You can add headers to the message (which can later be detected by
your filtering rules), and you can also choose other actions such as moving the message to a
folder, forwarding it to another address, or deleting it.

If a message has a weight greater than the activation weight... When a message has a weight
higher than the activation weight, either because it appears in the blacklist, or because its cal-
culated weight after rule processing exceeds your predetermined value, the action you select
here will be taken on the message. Some actions have a parameter (for instance, when you
select Forwarding, the parameter is the address to which the message should be forwarded).
The following actions are possible:

• Take no further action This action is useful if you want to turn off processing for a
while, but still want the mail to be marked as "processed". This option is also useful if
you only want standard headers added to messages as they pass through Content Control
(see below for more information on adding standard headers) - you will typically select
this case when you want to use filtering rules to handle such messages at a later stage.

• Add an identifying header If you select this action, Mercury will add an identifying
header to the headers of the message but will not otherwise divert or alter the message.
Whatever string you enter in the parameter field, Mercury will add as a header in the
delivered message, completely unmodified (so, you must include the header keyword,
the colon character, and the header body exactly as you want them to appear in the mes-
sage). You can use this action as well as using the standard "graphical" and diagnostic
headers (see below).