MailEnable Standard Guide
SMTP - Inbound
Services and Connectors > SMTP Connector > SMTP - Inbound



SMTP service listens on port

Determines the port the SMTP service is running on. The default is 25. Inbound SMTP connections from remote servers expect the mail server to be listening on port 25, but some proxy or gateway software may require this to be changed.

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.

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 bytes. 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

Checks each inbound message size after it is received. 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..

IP Address Connection Restrictions

Access Control

Specify who can connect to the email server. 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.

Allow IPv6 client connectivity  Enabling this option will will allow connections from clients using IPv6 addresses.