Mail domain name – If you are setting up NIS+ as your primary name service, sendmail can check the mail domain from the NIS+ sendmailvars table. This NIS+ table has one key column and one value column. To set up your mail domain, you must add one entry to this table. This entry should have the key column set to the literal string maildomain and the value column set to your mail domain name. An example is admin.acme.com. Although NIS+ allows any string in the sendmailvars table, the suffix rule still applies for the mail system to work correctly. You can use nistbladm to add the maildomain entry to the sendmailvars table. Notice in the following example that the mail domain is a suffix of the NIS+ domain.
nistbladm -A key="maildomain" value=<mail domain> sendmailvars.org_dir.<NIS+ domain>
Mailhost host name – You must have a mailhost entry in the NIS+ hosts table.
Full host names – NIS+ “understands” the full host name. Following the regular NIS+ setup procedure satisfies this requirement.
Matching full host names and short host names – To satisfy this requirement, you can duplicate the entries in the host table. Otherwise, you can enter all host entries in the user name-service domains into a master host table at mail domain level.
Multiple NIS domains in one mail domain – To satisfy this requirement, you can duplicate the entries in all the host tables. Otherwise, you can type all host entries in the user name service domains into a master host table at mail domain level. Effectively, you are merging multiple host tables that are logical or physical into one host table. Therefore, the same host name cannot be reused in the multiple name service domain that shares a common mail domain.