The MMP does not make use of the PORT_ACCESS mapping table. If you wish to reject SMTP connections from certain IP addresses and you are using the MMP, you must use the TCPAccess option. The syntax of this option is the same as mailDomainAllowedServiceAccess (see Sun Java Communications Suite 5 Schema Reference). It is also described at 23.7.2 Filter Syntax.
It is possible to specify more than one LDAP server for the MMP so that if one fails another takes over. Modify your PopProxyAservice.cfg or ImapProxyAservice.cfg to the following:
default:LdapUrl "ldap://ldap01.yourdomain ldap02.yourdomain/o=internet"
Make sure there is a space between the host names in the above configuration.