ugldaphost base option specifies the LDAP server list for user/group lookup. Takes a space-separated string. A port may be specified by appending "
:port" to a host name in the list. If empty or not set, the loopback interface is used.
Normally this option is set to an appropriate value during initial configuration.
The MTA has a "twin" option,
ldap_host, which may be set to specify an MTA-specific override of this option's value.