LibraCyber ESG offers an additional content filtering check, that takes place before the message is sent to the security engine. Content filtering is useful to add very powerful and lightweight checks, matched against email body or headers, which will interfere with the normal flow of the email. A case when this feature is useful is when you want to redirect a message to another user on-the-fly.
In the table are displayed all the Content Filtering Rules available. You can filter out the rules by performing a Search. To delete one or more rules you can select them and click the Delete button in the table toolbar.
Creating a new rule
A content filtering rule is composed of two main parts: a Filter and an Action. To create a Content Filtering rule you can click on the New button on the table toolbar. Once you clicked the button, the below dialog appears.
Note: when the rule is created, it's Disabled by default. You can enable it by setting the Status to Enabled.
Filters
The Filter is the condition for which the Action must be performed.
You can filter messages by Expression, ESG will try the given Value (a word, phrase or regex) to specified message header(s) (when Type is Apply to Headers) or to the message body (if Type is Apply to Body).
You can create more filters that ESG runs in the given Sequence. This is an order, so a rule having a greater value will be executed after an other rule having a smaller value.
Note: since content checks are executed before the security engine, the email body is processed as-in in the received email; this means, for example, that if the body is in a quoted-printable format the specified value should also be in quoted-printable format.
Actions
An Action is then executed when a Filter is matched. Available Actions are:
- Delete (Blackhole): this action will delete the incoming message without leaving any track in the database.
- Redirect to relay
- Redirect to User: will silently rewrite the destination address and the original recipient will not receive the email.
- SMTP Reject
- Add Custom Header
- BCC to user
- Replace Text
Warning: when you edited the table, you must click the Apply Settings button from the table toolbar to make changes effective.