diff --git a/app/models/comment.rb b/app/models/comment.rb
index 2e28215..b625d6c 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -9,6 +9,7 @@ class Comment < ActiveRecord::Base
   # unauthenticated authors:
   validates_presence_of :name, :if => (lambda { |record| !record.email.blank? })
   validates_presence_of :email, :if => (lambda { |record| !record.name.blank? })
+  validates_format_of :email, :with => Noosfero::Constants::EMAIL_FORMAT, :if => (lambda { |record| !record.email.blank? })
 
   # require either a recognized author or an external person
   validates_presence_of :author_id, :if => (lambda { |rec| rec.name.blank? && rec.email.blank? })
diff --git a/test/unit/comment_test.rb b/test/unit/comment_test.rb
index ff62846..afa9ba0 100644
--- a/test/unit/comment_test.rb
+++ b/test/unit/comment_test.rb
@@ -41,7 +41,7 @@ class CommentTest < Test::Unit::TestCase
     # if given name, require email
     c1 = Comment.new
     c1.name = 'My Name'
-    assert_mandatory c1, :email
+    assert_mandatory c1, :email, 'my@email.com'
 
     # if given email, require name
     c2 = Comment.new
@@ -137,5 +137,10 @@ class CommentTest < Test::Unit::TestCase
     assert_equal comments, Comment.recent(2)
   end
 
+  should 'not accept invalid email' do
+    c = Comment.new(:name => 'My Name', :email => 'my@invalid')
+    c.valid?
+    assert c.errors.invalid?(:email)
+  end
 
 end
--
libgit2 0.21.2