Create the admin email select box which queries through both projects and groups.

app/assets/javascripts/admin_email_select.js.coffee

+class @AdminEmailSelect
+  constructor: ->
+    $('.ajax-admin-email-select').each (i, select) =>
+      skip_ldap = $(select).hasClass('skip_ldap')
+
+      $(select).select2
+        placeholder: "Select group or project"
+        multiple: $(select).hasClass('multiselect')
+        minimumInputLength: 0
+        query: (query) ->
+          group_result = Api.groups query.term, skip_ldap, (groups) ->
+            groups
+
+          project_result = Api.projects query.term, (projects) ->
+            projects
+
+          $.when(project_result, group_result).done (projects, groups) ->
+            data = $.merge(groups[0], projects[0])
+            query.callback({ results: data})
+
+        formatResult: (args...) =>
+          @formatResult(args...)
+        formatSelection: (args...) =>
+          @formatSelection(args...)
+        dropdownCssClass: "ajax-admin-email-dropdown"
+        escapeMarkup: (m) -> # we do not want to escape markup since we are displaying html in results
+          m
+
+  formatResult: (object) ->
+    if object.path_with_namespace
+      "<div class='project-result'>
+         <div class='project-name'>#{object.name}</div>
+         <div class='project-path'>#{object.path_with_namespace}</div>
+       </div>"
+    else
+      "<div class='group-result'>
+         <div class='group-name'>#{object.name}</div>
+         <div class='group-path'>#{object.path}</div>
+       </div>"
+
+  formatSelection: (object) ->
+    if object.path_with_namespace
+      "Project: #{object.name}"
+    else
+      "Group: #{object.name}"
+

app/assets/javascripts/dispatcher.js.coffee

@@ -81,6 +81,8 @@ class Dispatcher
         new User()
       when 'projects:group_links:index'
         new GroupsSelect()
+      when 'admin:emails:show'
+        new AdminEmailSelect()
 
     switch path.first()
       when 'admin'

app/helpers/selects_helper.rb

@@ -35,4 +35,13 @@ module SelectsHelper
 
     hidden_field_tag(id, value, class: css_class)
   end
+
+  def admin_email_select_tag(id, opts = {})
+    css_class = "ajax-admin-email-select "
+    css_class << "multiselect " if opts[:multiple]
+    css_class << (opts[:class] || '')
+    value = opts[:selected] || ''
+
+    hidden_field_tag(id, value, class: css_class)
+  end
 end

app/views/admin/emails/show.html.haml

@@ -17,6 +17,6 @@
   .form-group
     %label.control-label{for: :recipients} Recipient group
     .col-sm-10
-      = select_tag :recipients, admin_email_grouped_recipient_options, class: :select2, required: true
+      = admin_email_select_tag(:recipients)
   .form-actions
     = submit_tag 'Send message', class: 'btn btn-create'