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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.

# IPS tab

Automatically detect and inspect the protocol | If this protocol has been enabled, it will automatically be used for discovering corresponding packets in filter rules.

## SMTP protocol extensions

Filter the CHUNKING extension | Allows filtering data transferred from one e-mail address to another. Example: Attachments in e-mails.
Filter Microsoft Exchange Server extensions | Allows filtering additional commands from the Microsoft Exchange Server.
Filter request to change connection direction (ATRN, ETRN) | Allows filtering data contained in the request to change connection direction, from the client to the server, or from the server to the client. During an SMTP communication, the use of ATRN and ETRN commands allows exchanging the client/server roles.

## Maximum size of elements (bytes)

Imposing a maximum size for elements (in bytes) allows countering buffer overflow attacks.

Message header [64 – 4096] | Maximum number of characters that an e-mail header can contain (e-mail address of the sender, date, type of encoding used, etc.).
Server response line [64 – 4096] | Maximum number of characters that the response line from the SMTP server can contain.
Exchange data (XEXCH50)[102400 – 1073741824] | Maximum volume of data when transferring files in MBDEF format (Message Database Encoding Format).
BDAT extension header [102400 – 10485760] | Maximum volume of data sent using the BDAT command.
Command line [64 – 4096] | Maximum volume of data that a command line can contain (excluding the DATA command).

## Support

Disable intrusion prevention | When this option is selected, the analysis of the SMTP protocol will be disabled and traffic will be allowed if the filter policy allows it
Log each SMTP request | Enables or disables the logging of SSL requests.