diff --git a/frontend/package.json b/frontend/package.json
index bc36fed58..779c6f2ea 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -94,6 +94,7 @@
     "color-blend": "4.0.0",
     "damerau-levenshtein": "1.0.8",
     "date-fns": "3.6.0",
+    "disposable-email-domains-js": "^1.0.35",
     "firebase": "12.0.0",
     "hangul-js": "0.2.6",
     "howler": "2.2.3",
diff --git a/frontend/src/ts/pages/login.ts b/frontend/src/ts/pages/login.ts
index 44cc80178..5d1d0b84f 100644
--- a/frontend/src/ts/pages/login.ts
+++ b/frontend/src/ts/pages/login.ts
@@ -80,9 +80,25 @@ validateWithIndicator(nameInputEl, {
   },
 });
 
+let disposableEmailModule: typeof import("disposable-email-domains-js") | null =
+  null;
+let moduleLoadAttempted = false;
+
 const emailInputEl = document.querySelector(
   ".page.pageLogin .register.side input.emailInput"
 ) as HTMLInputElement;
+
+emailInputEl.addEventListener("focus", async () => {
+  if (!moduleLoadAttempted) {
+    moduleLoadAttempted = true;
+    try {
+      disposableEmailModule = await import("disposable-email-domains-js");
+    } catch (e) {
+      // Silent failure
+    }
+  }
+});
+
 validateWithIndicator(emailInputEl, {
   schema: UserEmailSchema,
   isValid: async (email: string) => {
@@ -103,6 +119,23 @@ validateWithIndicator(emailInputEl, {
         warning: "Please check your email address, it may contain a typo.",
       };
     }
+
+    if (
+      disposableEmailModule &&
+      disposableEmailModule.isDisposableEmail !== undefined
+    ) {
+      try {
+        if (disposableEmailModule.isDisposableEmail(email)) {
+          return {
+            warning:
+              "Using a temporary email may cause issues with logging in, password resets and support. Consider using a permanent email address. Don't worry, we don't send spam.",
+          };
+        }
+      } catch (e) {
+        // Silent failure
+      }
+    }
+
     return true;
   },
   debounceDelay: 0,
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 388991d25..6a46dd27a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -312,6 +312,9 @@ importers:
       date-fns:
         specifier: 3.6.0
         version: 3.6.0
+      disposable-email-domains-js:
+        specifier: ^1.0.35
+        version: 1.16.0
       firebase:
         specifier: 12.0.0
         version: 12.0.0
@@ -4627,6 +4630,9 @@ packages:
   discontinuous-range@1.0.0:
     resolution: {integrity: sha512-c68LpLbO+7kP/b1Hr1qs8/BJ09F5khZGTxqxZuhzxpmwJKOgRFHJWIb9/KmqnqHhLdO55aOxFH/EGBvUQbL/RQ==}
 
+  disposable-email-domains-js@1.16.0:
+    resolution: {integrity: sha512-5BTVWEfUO1xeJ/jQdt+bIeOFYlgKuN5wGUtiMlkj0rqqpeO8LwiIH+7sKYvob87yMBjDKJWD8eqSSHFVM0g2pQ==}
+
   docker-compose@1.2.0:
     resolution: {integrity: sha512-wIU1eHk3Op7dFgELRdmOYlPYS4gP8HhH1ZmZa13QZF59y0fblzFDFmKPhyc05phCy2hze9OEvNZAsoljrs+72w==}
     engines: {node: '>= 6.0.0'}
@@ -14221,6 +14227,8 @@ snapshots:
 
   discontinuous-range@1.0.0: {}
 
+  disposable-email-domains-js@1.16.0: {}
+
   docker-compose@1.2.0:
     dependencies:
       yaml: 2.5.0