Sendmail Aliases/Groups
From KlavoWiki
Aliases
To send an email to an alias edit:
/etc/aliases
name: email@address.com
Groups
To send an email to a group of people:
/etc/aliases
groupname: email@addres1.com, email@address2.com ....
Restart Sendmail
So sendmail sees the changes you will need to restart the sendmail service.
service sendmail restart