diff --git a/seahub/base/accounts.py b/seahub/base/accounts.py
index e720045850..ee87d2e9a7 100644
--- a/seahub/base/accounts.py
+++ b/seahub/base/accounts.py
@@ -1,4 +1,6 @@
 # encoding: utf-8
+import re
+
 from django import forms
 from django.core.mail import send_mail
 from django.utils import translation
@@ -530,9 +532,15 @@ class RegistrationForm(forms.Form):
     password2 = forms.CharField(widget=forms.PasswordInput(attrs=attrs_dict, render_value=False),
                                 label=_("Password (again)"))
 
+    @classmethod
+    def allow_register(self, email):
+        prog = re.compile(r"(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)",
+                          re.IGNORECASE)
+        return False if prog.match(email) is None else True
+
     def clean_email(self):
         email = self.cleaned_data['email']
-        if not is_valid_username(email):
+        if not self.allow_register(email):
             raise forms.ValidationError(_("Enter a valid email address."))
 
         emailuser = ccnet_threaded_rpc.get_emailuser(email)
diff --git a/tests/seahub/base/test_accounts.py b/tests/seahub/base/test_accounts.py
index d89beadde2..842a6e7018 100644
--- a/tests/seahub/base/test_accounts.py
+++ b/tests/seahub/base/test_accounts.py
@@ -1,5 +1,5 @@
 from seahub.test_utils import BaseTestCase
-from seahub.base.accounts import User
+from seahub.base.accounts import User, RegistrationForm
 
 from post_office.models import Email
 
@@ -15,3 +15,38 @@ class UserTest(BaseTestCase):
         assert len(Email.objects.all()) > 0
         # email = Email.objects.all()[0]
         # print email.html_message
+
+
+class RegistrationFormTest(BaseTestCase):
+    def setUp(self):
+        self.valid_emails = [
+            'a@1.com',
+            'a.1@1.com',
+            'a+.1@1.com-pany',
+            'a+-_.1@1.com-pany',
+        ]
+
+        self.invalid_emails = [
+            '"a"@1.com',
+            '<script>@1.com',
+            '//@1.com',
+            'a+.-{}?1@1.com',
+            'a+.-()1@1.com',
+        ]
+
+        self.form_class = RegistrationForm
+
+    def test_allow_register(self):
+        for e in self.valid_emails:
+            assert self.form_class.allow_register(e) is True
+
+        for e in self.invalid_emails:
+            assert self.form_class.allow_register(e) is False
+
+    def test_clean_email(self):
+        form = self.form_class({'email': 'some_random_user@1.com',
+                                'password1': '123',
+                                'password2': '123',
+                            })
+        assert form.is_valid() is True
+        assert form.clean_email() == 'some_random_user@1.com'