Set mailname for onion only installs

src/freedombone-utils-final

@@ -140,6 +140,8 @@ function final_set_onion_hostname {
     hostname "$onion_domain"
 
     echo "127.0.1.1  $onion_domain" >> /etc/hosts
+
+    echo "$onion_domain" > /etc/mailname
 }
 
 function setup_final {