SMTP advanced delivery settings

SMTP Advanced Settings—Delivery Configuration describes SMTP delivery configuration message settings for your site.
SMTP Advanced Settings—Delivery Configuration
Item
Description
Maximum number of external connections
Sets the maximum number of simultaneous external connections. The default is 100 connections.
Maximum number of external connections to a single IP address
Sets the maximum number of simultaneous connections made to a single IP address. The default is 50 connections.
Maximum number of connections to all internal mail servers
Sets the maximum number of connections that can be made to all defined internal mail servers. The default is 100 internal mail server connections.
Maximum number of connections per single internal mail server
Sets the maximum number of connections to one internal mail server. The default is 50 connections.
Maximum number of messages in delivery queue
Sets the maximum threshold. When this threshold is met or exceeded, alerts are sent (when enabled) or connections are deferred. The default is 150,000 messages.
Maximum number of recipients per message in delivery queue
Specifies the number of recipients that are allowed per message in the delivery queue when recipients are batched. If the number of recipients for a message exceeds this value, the message is bifurcated until each messages' list of recipients no longer exceeds the limit.
You can enter values from 1 to 1024. The default value is 100.
Maximum number of outgoing messages for a connection
Sets the maximum threshold for the number of messages the MTA can send over a single connection. A setting of 0 disables the limit. The default setting is 0.
Defer new connections when delivery queue is full
When the number of messages in the delivery queue reaches or exceeds the maximum, defers messages, by issuing an SMTP 4xx error. If unchecked, messages are accepted for as long as resources allow.
Minimum retry interval
Sets the smallest interval the SMTP server waits before trying to deliver a message again. The default is 15 minutes.
Maximum retry interval
Sets the maximum interval the SMTP server waits before trying to deliver a message again. The default value is 7 hours.
Do not set this value to less than the value of the
Minimum retry interval
.
Sent message time-out
Sets the time after which an undelivered message times out and is rejected from the queue. The default is 5 days.
Bounce message time-out
Sets a time-out period for deletion of messages in your bounce queue. This can be particularly useful in environments where you cannot configure LDAP settings. The default is 1 day.
Message delay time in queue before notification
Sets the time a message waits in the mail queue before notification of nondelivery is sent. The default is 4 hours.
Attempt TLS encryption for all messages
Instructs the MTA to attempt TLS encryption for all messages delivered.
If you enable SSL Restrictions on the
Protocols > SMTP > Settings > SMTP
tab, SMG attempts encryption only with a supported TLS protocol.
Offer TLS client certificate
Instructs the MTA to offer a client certificate with every TLS connection.
Connection timeout
The amount of time in seconds to spend waiting for the connect system call to return. The default value is 30 seconds.
EHLO/HELO timeout
The amount of time in seconds to wait for a response to the
EHLO
or
HELO
command. The default value is 5 minutes.
MAIL FROM timeout
The amount of time in seconds to wait for a response from the
MAIL FROM
command. The default value is 5 minutes.
RCPT TO timeout
The amount of time in seconds to wait for a response to the
RCPT TO
command. The default value is 5 minutes.
DATA timeout
The amount of time in seconds to wait for a response once the DATA phase is terminated by a CRLF.CRLF. This timeout is relatively long because it is the only phase of transmission which involves significant network transmission. The default value is 10 minutes.
RSET timeout
The amount of time to wait for a response to a
RSET
command.
RSET
commands are used to reset the state of an SMTP session in which a transaction has only partially succeeded. It allows subsequent messages to be delivered down a single SMTP session immediately following a transient or permanent failure response from the remote server before the complete and successful delivery of the previous message. The default value is 10 minutes.
Idle timeout
The amount of time in seconds to hold open an idle connection when there are no messages currently deliverable for that domain. The default value is 5 seconds.