Configuring an IPv6 daemon and relay client (optional)

Depending on your system's environment, select one of the following sendmail configuration statements.

To listen on IPv4 interfaces only, use the following statement:

DAEMON_OPTIONS(`Name=MTA-v4, Family=inet')

To listen on both IPv4 and IPv6 interfaces, use the following statement:

DAEMON_OPTIONS(`Name=MTA-v6, Family=inet6')

To set a restriction for outgoing connections on a particular family, use ClientPortOptions in the configuration file. For example, the following statement indicates that sendmail is a relay client for the IPv6 family.

CLIENT_OPTIONS(Family=inet6);

Note: If the following message is shown in the log file when invoking the sendmail daemon, check that your system supports IPv6. If your system has no IPv6 capability, sendmail will fail to start the daemon.

opendaemonsocket: daemon MTA-v6: can't create server SMTP socket"
opendaemonsocket: daemon MTA-v6: problem creating SMTP socket"