diff --git a/mail/base/content/mailWindow.js b/mail/base/content/mailWindow.js
index 330eb473b6..02259b3255 100644
--- a/mail/base/content/mailWindow.js
+++ b/mail/base/content/mailWindow.js
@@ -299,12 +299,9 @@ function InitMsgWindow() {
       }
     },
   };
-  Services.els.addSystemEventListener(
-    document,
-    "keypress",
-    keypressListener,
-    false
-  );
+  document.addEventListener("keypress", keypressListener, {
+    mozSystemGroup: true,
+  });
 }
 
 // We're going to implement our status feedback for the mail window in JS now.
diff --git a/mail/components/customizableui/CustomizableUI.sys.mjs b/mail/components/customizableui/CustomizableUI.sys.mjs
index 534ede9d04..d855ee3114 100644
--- a/mail/components/customizableui/CustomizableUI.sys.mjs
+++ b/mail/components/customizableui/CustomizableUI.sys.mjs
@@ -20,8 +20,8 @@ var gPanelsForWindow = new WeakMap();
 
 var CustomizableUIInternal = {
   addPanelCloseListeners(aPanel) {
-    Services.els.addSystemEventListener(aPanel, "click", this, false);
-    Services.els.addSystemEventListener(aPanel, "keypress", this, false);
+    aPanel.addEventListener("click", this, { mozSystemGroup: true });
+    aPanel.addEventListener("keypress", this, { mozSystemGroup: true });
     const win = aPanel.ownerGlobal;
     if (!gPanelsForWindow.has(win)) {
       gPanelsForWindow.set(win, new Set());
@@ -30,8 +30,8 @@ var CustomizableUIInternal = {
   },
 
   removePanelCloseListeners(aPanel) {
-    Services.els.removeSystemEventListener(aPanel, "click", this, false);
-    Services.els.removeSystemEventListener(aPanel, "keypress", this, false);
+    aPanel.removeEventListener("click", this, { mozSystemGroup: true });
+    aPanel.removeEventListener("keypress", this, { mozSystemGroup: true });
     const win = aPanel.ownerGlobal;
     const panels = gPanelsForWindow.get(win);
     if (panels) {