See the Red Hat Enterprise Linux 7 Networking Guide for more information on recommended naming practices.
It is important to be aware of what Sendmail is and what it can do, as opposed to what it is not.
In these days of monolithic applications that fulfill multiple roles, Sendmail may seem like the only application needed to run an email server within an organization.
But if I try to use an alias, sendmail never expands the alias and just tries to send the mail as the alias.
For example, in /etc/mail/aliases I have an entry that says: EHLO Mserver.250-Mserver.Hello server A.[192.168.0.4], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-EXPN 250-VERB 250-8BITMIME 250-SIZE 10485760 250-DSN 250-ETRN 250-DELIVERBY 250 HELP Check your access database (/etc/mail/access*) - you probably have to 'tell' sendmail you will accept mail from server A.
If Procmail is available, it is launched to filter the email and place it in a mailbox so that it can be read by an MUA.