diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 8fa56ac55b..0b0dd01e58 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -54,7 +54,8 @@ module ApplicationHelper
       name = h(user.name(options[:format]))
       if user.active? || (User.current.admin? && user.logged?)
         only_path = options[:only_path].nil? ? true : options[:only_path]
-        link_to name, user_url(user, :only_path => only_path), :class => user.css_classes
+        css_classes = options[:class] ? "#{user.css_classes} #{options[:class]}" : user.css_classes
+        link_to name, user_url(user, :only_path => only_path), :class => css_classes
       else
         name
       end
@@ -974,9 +975,6 @@ module ApplicationHelper
               if p = Project.visible.find_by_id(oid)
                 link = link_to_project(p, {:only_path => only_path}, :class => 'project')
               end
-            when 'user'
-              u = User.visible.find_by(:id => oid, :type => 'User')
-              link = link_to_user(u, :only_path => only_path) if u
             end
           elsif sep == ':'
             name = remove_double_quotes(identifier)
@@ -1035,14 +1033,14 @@ module ApplicationHelper
               if p = Project.visible.where("identifier = :s OR LOWER(name) = :s", :s => name.downcase).first
                 link = link_to_project(p, {:only_path => only_path}, :class => 'project')
               end
-            when 'user'
-              u = User.visible.find_by("LOWER(login) = :s AND type = 'User'", :s => name.downcase)
-              link = link_to_user(u, :only_path => only_path) if u
             end
-          elsif sep == "@"
-            name = remove_double_quotes(identifier)
-            u = User.visible.find_by("LOWER(login) = :s AND type = 'User'", :s => name.downcase)
-            link = link_to_user(u, :only_path => only_path) if u
+          end
+          if link.nil? && $~
+            user = User.mentioned_user($~.named_captures.symbolize_keys)
+            if user
+              css_classes = (user.notify_mentioned_user?(obj) ? 'notified' : nil)
+              link = link_to_user(user, :only_path => only_path, :class => css_classes)
+            end
           end
         end
         (leading + (link || "#{project_prefix}#{prefix}#{repo_prefix}#{sep}#{identifier}#{comment_suffix}"))
diff --git a/app/models/document.rb b/app/models/document.rb
index ccf750fc68..603a535cab 100644
--- a/app/models/document.rb
+++ b/app/models/document.rb
@@ -61,7 +61,7 @@ class Document < ActiveRecord::Base
   end
 
   def notified_users
-    project.notified_users.reject {|user| !visible?(user)}
+    project.notified_users.select {|user| user.allowed_to_view_notify_target?(self) }
   end
 
   private
diff --git a/app/models/issue.rb b/app/models/issue.rb
index b20da8d91c..435de5912a 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1038,8 +1038,7 @@ class Issue < ActiveRecord::Base
     notified += project.notified_users
     notified.uniq!
     # Remove users that can not view the issue
-    notified.reject! {|user| !visible?(user)}
-    notified
+    notified.select {|user| user.allowed_to_view_notify_target?(self)}
   end
 
   # Returns the email addresses that should be notified
diff --git a/app/models/journal.rb b/app/models/journal.rb
index ce3f9d0b32..6bf9690254 100644
--- a/app/models/journal.rb
+++ b/app/models/journal.rb
@@ -141,10 +141,7 @@ class Journal < ActiveRecord::Base
 
   def notified_users
     notified = journalized.notified_users
-    if private_notes?
-      notified = notified.select {|user| user.allowed_to?(:view_private_notes, journalized.project)}
-    end
-    notified
+    notified.select{ |u| u.allowed_to_view_notify_target?(self) }
   end
 
   def recipients
diff --git a/app/models/mailer.rb b/app/models/mailer.rb
index 92432cf096..350640eb30 100644
--- a/app/models/mailer.rb
+++ b/app/models/mailer.rb
@@ -90,6 +90,7 @@ class Mailer < ActionMailer::Base
   #   Mailer.deliver_issue_add(issue)
   def self.deliver_issue_add(issue)
     users = issue.notified_users | issue.notified_watchers
+    users |= mentioned_users(issue.description, issue)
     users.each do |user|
       issue_add(user, issue).deliver_later
     end
@@ -124,6 +125,7 @@ class Mailer < ActionMailer::Base
   #   Mailer.deliver_issue_edit(journal)
   def self.deliver_issue_edit(journal)
     users  = journal.notified_users | journal.notified_watchers
+    users |= mentioned_users(journal.notes, journal)
     users.select! do |user|
       journal.notes? || journal.visible_details(user).any?
     end
@@ -149,6 +151,7 @@ class Mailer < ActionMailer::Base
   #   Mailer.deliver_document_added(document, author)
   def self.deliver_document_added(document, author)
     users = document.notified_users
+    users |= mentioned_users(document.description, document)
     users.each do |user|
       document_added(user, document, author).deliver_later
     end
@@ -217,6 +220,7 @@ class Mailer < ActionMailer::Base
   #   Mailer.deliver_news_added(news)
   def self.deliver_news_added(news)
     users = news.notified_users | news.notified_watchers_for_added_news
+    users |= mentioned_users(news.description, news)
     users.each do |user|
       news_added(user, news).deliver_later
     end
@@ -244,6 +248,7 @@ class Mailer < ActionMailer::Base
   def self.deliver_news_comment_added(comment)
     news = comment.commented
     users = news.notified_users | news.notified_watchers
+    users |= mentioned_users(comment.content, news)
     users.each do |user|
       news_comment_added(user, comment).deliver_later
     end
@@ -271,6 +276,7 @@ class Mailer < ActionMailer::Base
     users  = message.notified_users
     users |= message.root.notified_watchers
     users |= message.board.notified_watchers
+    users |= mentioned_users(message.content, message)
 
     users.each do |user|
       message_posted(user, message).deliver_later
@@ -329,6 +335,7 @@ class Mailer < ActionMailer::Base
     users  = wiki_content.notified_users
     users |= wiki_content.page.notified_watchers
     users |= wiki_content.page.wiki.notified_watchers
+    users |= mentioned_users(wiki_content.text, wiki_content)
 
     users.each do |user|
       wiki_content_updated(user, wiki_content).deliver_later
@@ -758,5 +765,16 @@ class Mailer < ActionMailer::Base
     @references_objects ||= []
     @references_objects << object
   end
+
+  def self.mentioned_users(text, obj)
+    users = []
+    return users if text.blank?
+    text.scan(ApplicationHelper::LINKS_RE) do |_|
+      target = User.mentioned_user($~.named_captures.symbolize_keys)
+      next if target.blank? || users.include?(target)
+      users << target if target.notify_mentioned_user?(obj)
+    end
+    users
+  end
 end
 
diff --git a/app/models/message.rb b/app/models/message.rb
index 83e8cd2c02..cb244defb6 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -103,7 +103,7 @@ class Message < ActiveRecord::Base
   end
 
   def notified_users
-    project.notified_users.reject {|user| !visible?(user)}
+    project.notified_users.select {|user| user.allowed_to_view_notify_target?(self) }
   end
 
   private
diff --git a/app/models/news.rb b/app/models/news.rb
index 90df77e326..d705243d13 100644
--- a/app/models/news.rb
+++ b/app/models/news.rb
@@ -54,7 +54,7 @@ class News < ActiveRecord::Base
   end
 
   def notified_users
-    project.users.select {|user| user.notify_about?(self) && user.allowed_to?(:view_news, project)}
+    project.users.select {|user| user.notify_about?(self) && user.allowed_to_view_notify_target?(self)}
   end
 
   def recipients
diff --git a/app/models/user.rb b/app/models/user.rb
index 0f82a68068..531f73ab97 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -787,6 +787,17 @@ class User < Principal
     end
   end
 
+  # Return true if the user is allowed to view the notify target.
+  def allowed_to_view_notify_target?(object)
+    case object
+    when Journal
+      self.allowed_to_view_notify_target?(object.journalized) &&
+        (!object.private_notes? || self.allowed_to?(:view_private_notes, object.journalized.project))
+    else
+      object.try(:visible?, self)
+    end
+  end
+
   def self.current=(user)
     RequestStore.store[:current_user] = user
   end
@@ -795,6 +806,32 @@ class User < Principal
     RequestStore.store[:current_user] ||= User.anonymous
   end
 
+  # Return the mentioned user to based on the match data
+  #  of ApplicationHelper::LINKS_RE.
+  #     user:jsmith -> Link to user with login jsmith
+  #     @jsmith -> Link to user with login jsmith
+  #     user#2 -> Link to user with id 2
+  def self.mentioned_user(match_data)
+    return nil if match_data[:esc]
+    sep = match_data[:sep1] || match_data[:sep2] || match_data[:sep3] || match_data[:sep4]
+    identifier = match_data[:identifier1] || match_data[:identifier2] || match_data[:identifier3]
+    prefix = match_data[:prefix]
+    if (sep == '#' || sep == '##') && prefix == 'user'
+      User.visible.find_by(:id => identifier.to_i, :type => 'User')
+    elsif sep == '@' || (sep == ':' && prefix == 'user')
+      name = identifier.gsub(%r{^"(.*)"$}, "\\1")
+      User.find_by_login(CGI.unescapeHTML(name).downcase)
+    end
+  end
+
+  # Return true if notify the mentioned user.
+  def notify_mentioned_user?(object)
+    self.active? &&
+      self.mail.present? &&
+      self.mail_notification.present? && self.mail_notification != 'none' &&
+      self.allowed_to_view_notify_target?(object)
+  end
+
   # Returns the anonymous user.  If the anonymous user does not exist, it is created.  There can be only
   # one anonymous user per database.
   def self.anonymous
diff --git a/app/models/wiki_content.rb b/app/models/wiki_content.rb
index 32e0c84508..85c5535bb8 100644
--- a/app/models/wiki_content.rb
+++ b/app/models/wiki_content.rb
@@ -51,7 +51,7 @@ class WikiContent < ActiveRecord::Base
   end
 
   def notified_users
-    project.notified_users.reject {|user| !visible?(user)}
+    project.notified_users.select {|user| user.allowed_to_view_notify_target?(self) }
   end
 
   # Returns the mail addresses of users that should be notified
diff --git a/test/unit/mailer_test.rb b/test/unit/mailer_test.rb
index 2f92d1c603..f1aaca9328 100644
--- a/test/unit/mailer_test.rb
+++ b/test/unit/mailer_test.rb
@@ -365,6 +365,28 @@ class MailerTest < ActiveSupport::TestCase
     assert_include 'dlopper@somenet.foo', recipients
   end
 
+  def test_issue_added_should_notify_mentioned_users
+    # issue with non-public project
+    issue = Issue.find(4)
+    # Developer
+    user = User.find(8)
+
+    # notify mentioned user
+    ["user##{user.id}", "@#{user.login}", "user:#{user.login}"].each do |description|
+      issue.update(description: description)
+      ActionMailer::Base.deliveries.clear
+      Mailer.deliver_issue_add(issue)
+      assert_include user.mail, recipients
+    end
+
+    # Do not notify mentioned users without view_issues permission.
+    Role.find(2).remove_permission!(:view_issues)
+    issue.update(description: "user##{user.id}")
+    ActionMailer::Base.deliveries.clear
+    Mailer.deliver_issue_add(issue)
+    assert_not_include user.mail, recipients
+  end
+
   def test_issue_add_should_send_mail_to_all_user_email_address
     EmailAddress.create!(:user_id => 3, :address => 'otheremail@somenet.foo')
     issue = Issue.find(1)