SMTP Enable SSL (Default Port) (Enterprise Edition only)
Enables SSL certificate encryption for the default port that SMTP is running on. Place a tick in this box to enable. The service also has to be enabled at a server level in the MailEnable Administration Program > Server >Localhost Properties > SSL tab.
Also listen on alternate port
The SMTP service can also listen on an alternate port by enabling this option. Usually this is done to cater for clients who may be on connections where their outgoing port 25 has been blocked.
SMTP Enable SSL (Alternate Port) (Enterprise Edition only)
Enables SSL certificate encryption for the alternate port that SMTP is running on. The default port for this is 465. When enabling SSL make sure that a valid SSL certificate has been selected in the MailEnable Administration >Server > Localhost Properties >SSL tab.
Maximum number of concurrent connections
The number of connections that will be available for remote servers and email clients to connect to.
Advertised Maximum message size
Entering a value here will inform remote mail servers and email clients of the maximum size of an email that should be sent to the server. The size is represented in kilobytes. Clients or remote mail servers may ignore the value. A size of 0 means that there is no limit on message size.
Enforce this message size
Will check each inbound message size after it is received and if it is over the limit it will be deleted and an error returned to the remote server or email client that is trying to send.
Access Control
The Access Control feature specifies who can connect to the email server. It is possible to specify a list of IP addresses that are either banned from connecting, or are the only ones allowed to connect. Use the * character as a wildcard.
Inbound IP Bindings
Select the IP addresses that the SMTP service will be bound to. On a multi-homed machine it may desirable to only listen to connections on particular IP addresses. ‘Always bind the service to all available IP addresses’ will allow connections on all IP addresses that are configured for the machine.