diff --git a/seahub/base/templatetags/seahub_tags.py b/seahub/base/templatetags/seahub_tags.py
index 825629e1e4..0a76de8174 100644
--- a/seahub/base/templatetags/seahub_tags.py
+++ b/seahub/base/templatetags/seahub_tags.py
@@ -356,20 +356,24 @@ def translate_seahub_time_str(val):
 @register.filter(name='email2nickname')
 def email2nickname(value):
     """
-    Return nickname or short email.
+    Return nickname if it exists and it's not an empty string,
+    otherwise return short email.
     """
     if not value:
         return ''
 
     key = normalize_cache_key(value, NICKNAME_CACHE_PREFIX)
-    nickname = cache.get(key)
-    if not nickname:
-        profile = get_first_object_or_none(Profile.objects.filter(user=value))
-        if profile is not None and profile.nickname:
-            nickname = profile.nickname
-        else:
-            nickname = value.split('@')[0]
-        cache.set(key, nickname, NICKNAME_CACHE_TIMEOUT)
+    cached_nickname = cache.get(key)
+    if cached_nickname and cached_nickname.strip():
+        return cached_nickname.strip()
+
+    profile = get_first_object_or_none(Profile.objects.filter(user=value))
+    if profile is not None and profile.nickname and profile.nickname.strip():
+        nickname = profile.nickname.strip()
+    else:
+        nickname = value.split('@')[0]
+
+    cache.set(key, nickname, NICKNAME_CACHE_TIMEOUT)
     return nickname
 
 @register.filter(name='email2id')
diff --git a/tests/seahub/base/templatetags/test_seahub_tags.py b/tests/seahub/base/templatetags/test_seahub_tags.py
new file mode 100644
index 0000000000..f78389b647
--- /dev/null
+++ b/tests/seahub/base/templatetags/test_seahub_tags.py
@@ -0,0 +1,32 @@
+from seahub.test_utils import BaseTestCase
+
+from seahub.base.templatetags.seahub_tags import email2nickname
+from seahub.profile.models import Profile
+
+
+class Email2nicknameTest(BaseTestCase):
+    def test_profile_is_none(self):
+        assert len(Profile.objects.all()) == 0
+
+        assert email2nickname(self.user.username) == self.user.username.split('@')[0]
+
+    def test_nickname_is_empty_string(self):
+        Profile.objects.add_or_update(self.user.username, '')
+        assert len(Profile.objects.all()) == 1
+        assert Profile.objects.all()[0].nickname == ''
+
+        assert email2nickname(self.user.username) == self.user.username.split('@')[0]
+
+    def test_nickname_is_space(self):
+        Profile.objects.add_or_update(self.user.username, ' ')
+        assert len(Profile.objects.all()) == 1
+        assert Profile.objects.all()[0].nickname == ' '
+
+        assert email2nickname(self.user.username) == self.user.username.split('@')[0]
+
+    def test_nickname_contains_space(self):
+        Profile.objects.add_or_update(self.user.username, ' foo bar ')
+        assert len(Profile.objects.all()) == 1
+        assert Profile.objects.all()[0].nickname == ' foo bar '
+
+        assert email2nickname(self.user.username) == 'foo bar'