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IMPORTANT
SNS 3.x versions have reached End of Maintenance since July 1st, 2024.
We recommend that you update your SNS firewalls to a version with maintenance to guarantee the protection of your infrastructure.

# Rules

The procedure for editing an SMTP filter profile is as follows:

Select a profile from the list of URL filter profiles.

The table of filters will then appear as well as a screen indicating errors.

## Possible operations

The available buttons are:

Add | Inserts a line to be configured after the selected line.
Delete | Deletes the selected line.
Move up | Places the selected line before the line just above it.
Move down | Places the selected line after the line just below it.
Cut | Removes the selected line and moves it to the clipboard.
Copy | Copies the selected line and moves it to the clipboard.
Paste | Pastes the line from the clipboard above the selected line.

## Interactive features

Some operations listed in the taskbar can be performed by right-clicking on the table of filter rules:

- Add,
- Delete,
- Cut,
- Copy,
- Paste.

## The table

The table contains the following columns:

Status | Status of the rule: If Enabled, the rule is used for filtering. If Disabled, the rule is not used for filtering. If this rule is disabled, the line will be grayed out in order to reflect this. REMARK The firewall will assess rules in their order of appearance on the screen: one by one from the top down. As soon as it comes across a rule that corresponds to the request, it will perform the specified action and stop there. This means that if the action specified in the rule corresponds to Block, all rules below it will also be set to Block.
Action | Allows specifying the result of the rule: Pass to allow sending and receiving e-mails, Block to prohibit them
Sender | Defines the sender of the e-mail. The value “none” can be selected as a sender.
Recipient (to, cc, cci) | Defines the intended recipient of the e-mail.
Comments | Comments relating to the rule.

An e-mail mask may contain the following syntax:

- *: replaces a character string.

Example

*@company.com allows defining all e-mails from the internet domain of the company called COMPANY.

The following can also be seen:

- ? Replaces a character.
- <none>: This value can only be obtained when the Sender field is empty, and is used only for mailer daemons. When an e-mail cannot locate its recipient on a remote mail server, the remote mail server will send back an error message, indicating that there is an error regarding the recipient. In this case, the Sender field in this error message will be empty.

A rule with the action “Block” can be created to prevent the e-mail from being sent if the sender is unknown.

## Errors found in the SMTP filter policy

The screen for editing SMTP filter rules on the firewall has a rule compliance and coherence analyzer which warns the administrator when a rule inhibits another rule or if there is an error in a rule.

This analyzer groups errors during the creation of rules or incoherent rules.

Errors are displayed in the form of a list. By clicking on an error, the rule concerned will automatically be selected.