SMTP advanced authentication settings

SMTP Advanced Settings—SMTP Authentication Configuration describes the advanced authentication SMTP settings that you can use to further define your SMTP configuration.
SMTP Advanced Settings—SMTP Authentication Configuration
Item
Description
Maximum number of connections
Sets the maximum number of simultaneous SMTP authentication connections. The default is 2,000 connections.
Maximum number of connections from a single IPv4 address or IPv6 range
Sets the maximum number of simultaneous SMTP authentication connections that can be made from a single IPv4 address or IPv6 range.
The default value is 20 connections.
IPv6 CIDR prefix for maximum number of connections from a single IPv6 range
Describes the CIDR prefix to be used if an IPv6 range is used.
The prefix value must be an integer from 0 to 128. The default value is 64.
Maximum number of connections from a single IP address
Sets the maximum number of simultaneous SMTP authentication connections that can be made from a single IP address. The default is 20 connections.
Maximum message size in bytes
Sets the maximum size allowable for a message before it is rejected. The default is 10,485,760 bytes.
Maximum number of recipients per message
Indicates the maximum number of recipients permitted to receive a message. The default is 1,024 recipients.
Maximum number of messages per session
Indicates the maximum number of email messages that are permitted in a single session.
The default value is 100.
Insert RECEIVED header
Places a RECEIVED header in the message during outbound processing of messages sent using SMTP authentication when checked. When unchecked, no RECEIVED header is inserted during outbound SMTP processing. If this option and
Strip pre-existing RECEIVED headers
are both checked, the outbound SMTP RECEIVED header remains when the message goes to the delivery queue.
Strip RECEIVED headers
Removes all RECEIVED headers for outbound messages sent using SMTP authentication when checked. When headers are stripped, message looping can occur depending on the settings of other MTAs. When unchecked, RECEIVED headers remain in the message during outbound processing. The RECEIVED header for outbound SMTP processing remains in the message when both
Insert RECEIVED header
and
Strip pre-existing RECEIVED headers
are checked.
Enabling this setting can reduce you ability to diagnose message flow issues.
Enable reverse DNS lookup
Causes the system to perform reverse DNS lookup on the SMTP client IP addresses to resolve the IP address to a name when checked. This is the default condition. When unchecked, reverse DNS lookup is not performed for outbound messages sent using SMTP authentication.
When you enable the global reverse DNS settings on
Protocols > SMTP > Settings > SMTP
tab, under
DNS Validation
, you override this local setting.
Enable optional SASL plain support
By default, Symantec Messaging Gateway uses SASL login authentication. You can choose to also enable SASL plain authentication.
For more information, see the following RFCs:
Session timeout
This setting controls how long the MTA waits for a request or response from the connecting MTA. If this limit is exceeded, the appliance will drop the connection. The default value is 30 seconds.
The SMTP authentication listener uses the outbound message queue, and inherits some behavior from the outbound listener.