Add a distinct variable 'with_smtp_aliases' to install /etc/aliases only

group_vars/all

@@ -22,6 +22,7 @@ with_chkrootkit: True
 with_smartd: False
 
 with_smtp: False
+with_smtp_aliases: False
 
 with_ssh: True
 ssh_port: 2222

roles/common/tasks/smtp.yml

@@ -6,7 +6,7 @@
   action: template src=aliases.j2 dest=/etc/aliases owner=root group=root mode=0644
   notify:
     - Regenerate aliases cache
-  when_boolean: ${with_smtp}
+  when_boolean: ${with_smtp} or ${with_smtp_aliases}
 
 - name: Install postfix main configuration
   action: template src=postfix/main.cf.j2 dest=/etc/postfix/main.cf owner=root group=root mode=0644