diff --git a/src/backend/src/routers/signup.js b/src/backend/src/routers/signup.js
index d70d3d637..71f495792 100644
--- a/src/backend/src/routers/signup.js
+++ b/src/backend/src/routers/signup.js
@@ -189,7 +189,7 @@ module.exports = eggspress(['/signup'], {
     const svc_cleanEmail = req.services.get('clean-email');
     const clean_email = svc_cleanEmail.clean(req.body.email);
     
-    if (clean_email !== '' && ! await svc_cleanEmail.validate(clean_email) ) {
+    if (clean_email !== '' && !req.body.is_temp && ! await svc_cleanEmail.validate(clean_email) ) {
         return res.status(400).send('This email is not allowed.');
     }