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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.

# Proxy tab

Filter the welcome banner | When this option is selected, the server’s banner will become anonymous during an SMTP connection.

## HELO Command

Replace the client's domain name with its IP address | During a basic identification, the client enters its domain name by executing the HELO command. By selecting this option, the domain name will be replaced by the IP address.

## Filter domain name

Enable server’s domain name filtering | This option allows deleting the domain name of the SMTP server from its response to a HELO command coming from a client. This filter is enabled by default.

## Connection

Keep original source IP address | When a request is made by a web client (browser) to the server, the firewall will intercept it and check that the request complies with URL filter rules and then relays the request. If this option is selected, the new request will use the original source IP address of the web client that sent the packet. Otherwise, the firewall’s address will be used.

## Limits when sending an e-mail

By default, the data size limit for the outgoing mail message (text line) is enabled. Its maximum has been set to 1000 according to the RFC 2821.

Restrict the size of message lines | Sets a limit on the length of the lines in an outgoing message.
Message line [1000-2048 (KB)] | This field indicates the maximum length of a line when sending a message. REMARK Imposing a maximum size for elements (in bytes) allows countering buffer overflow attacks.
Max. no. of recipients | Indicates the maximum number of recipients that a message can contain. The firewall will refuse messages with too many recipients (the refusal will be indicated by an SMTP error). This allows restricting spam.
Maximum size of the message [0 – 2147483647 (KB)] | Indicates the maximum size of messages passing through the Stormshield Network firewall. Messages exceeding the defined size will be refused by the firewall.