diff --git a/app/models/user.rb b/app/models/user.rb
index c06a907fe..1b7680182 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -69,7 +69,7 @@ class User < Principal
   validates_format_of :login, :with => /^[a-z0-9_\-@\.]*$/i
   validates_length_of :login, :maximum => 30
   validates_length_of :firstname, :lastname, :maximum => 30
-  validates_format_of :mail, :with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i, :allow_nil => true
+  validates_format_of :mail, :with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i, :allow_blank => true
   validates_length_of :mail, :maximum => 60, :allow_nil => true
   validates_confirmation_of :password, :allow_nil => true
   validates_inclusion_of :mail_notification, :in => MAIL_NOTIFICATION_OPTIONS.collect(&:first), :allow_blank => true
diff --git a/test/unit/user_test.rb b/test/unit/user_test.rb
index 3848eab0f..0fbb7d0c9 100644
--- a/test/unit/user_test.rb
+++ b/test/unit/user_test.rb
@@ -41,6 +41,13 @@ class UserTest < ActiveSupport::TestCase
     u.mail = " foo@bar.com  "
     assert_equal "foo@bar.com", u.mail
   end
+  
+  def test_mail_validation
+    u = User.new
+    u.mail = ''
+    assert !u.valid?
+    assert_equal I18n.translate('activerecord.errors.messages.blank'), u.errors.on(:mail)
+  end
 
   def test_create
     user = User.new(:firstname => "new", :lastname => "user", :mail => "newuser@somenet.foo")