diff --git a/machines/vault01/ups.nix b/machines/vault01/ups.nix
index badda28..87642ca 100644
--- a/machines/vault01/ups.nix
+++ b/machines/vault01/ups.nix
@@ -18,12 +18,30 @@
       let
         cmdScript = pkgs.writeShellApplication {
           name = "upssched-cmd.sh";
-          runtimeInputs = with pkgs; [ systemd ];
+          runtimeInputs = with pkgs; [
+            systemd
+            msmtp
+          ];
           text = ''
             case $1 in
-              shutdown) shutdown now
-              # TODO : warn
-              # TODO : warn & log on unknown cmd
+              shutdown-low) MEANING="Battery is low, shutting down.";;
+              shutdown-batt) MEANING="On battery for 15min, shutting down.";;
+              warn-batt) MEANING="Power line faillure, going on battery.";;
+              warn-comm) MEANING="Communication with the UPS was broken.";;
+              warn-bypass) MEANING="The UPS is not protecting the server, power line failure would kill $HOSTNAME instantly.";;
+              *) MEANING="Signal unknown, check configuration.";;
+            esac
+            sendmail -i -t <<ERRMAIL
+            To: fai@dgnum.eu
+            Subject: [$HOSTNAME] Battery signal: $1
+            Content-Transfer-Encoding: 8bit
+            Content-Type: text/plain; charset=UTF-8
+
+            $MEANING
+            ERRMAIL
+
+            case $1 in
+              shutdown-*) shutdown 20s # let 20s to send the email
             esac
           '';
         };
@@ -31,10 +49,13 @@
           CMDSCRIPT ${cmdScript}/bin/upssched-cmd.sh
           PIPEFN /var/state/ups/upssched/upssched.pipe
           LOCKFN /var/state/ups/upssched/upssched.lock
-          AT LOWBATT * EXECUTE shutdown
-          AT ONBATT * START-TIMER shutdown 900
-          AT ONLINE * CANCEL-TIMER shutdown
-          # TODO : warn admins at COMMBAD NOCOMM BYPASS (and maybe at ONBATT)
+          AT LOWBATT * EXECUTE shutdown-low
+          AT ONBATT * EXECUTE warn-batt
+          AT ONBATT * START-TIMER shutdown-batt 900
+          AT ONLINE * CANCEL-TIMER shutdown-batt
+          AT COMMBAD * EXECUTE warn-comm
+          AT NOCOMM * EXECUTE warn-comm
+          AT BYPASS * EXECUTE warn-bypass
         '';
       in
       (pkgs.writeTextFile {