diff --git a/Changelog.md b/Changelog.md
index 8b8101347..53735b606 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -19,6 +19,7 @@
 * Add flash warning to conversation mobile, unification of flash warning with login and register mobile, and add support for flash warning to Opera browser. [#3686](https://github.com/diaspora/diaspora/pull/3686)
 * Add progress percentage to upload images. [#3740](https://github.com/diaspora/diaspora/pull/3740)
 * Mark all unread post-related notifications as read, if one of this gets opened. [#3787](https://github.com/diaspora/diaspora/pull/3787)
+* Add flash-notice when sending messages to non-contacts. [#3723](https://github.com/diaspora/diaspora/pull/3723)
 
 ## Bug Fixes
 
diff --git a/app/controllers/conversations_controller.rb b/app/controllers/conversations_controller.rb
index c4eae4a5d..acf91a70e 100644
--- a/app/controllers/conversations_controller.rb
+++ b/app/controllers/conversations_controller.rb
@@ -37,11 +37,14 @@ class ConversationsController < ApplicationController
     params[:conversation][:messages_attributes] = [ {:author => current_user.person, :text => message_text }]
 
     @conversation = Conversation.new(params[:conversation])
-    if @conversation.save
+    if person_ids.present? && @conversation.save
       Postzord::Dispatcher.build(current_user, @conversation).post
       flash[:notice] = I18n.t('conversations.create.sent')
     else
       flash[:error] = I18n.t('conversations.create.fail')
+      if person_ids.blank?
+        flash[:error] = I18n.t('conversations.create.no_contact')
+      end
     end
     if params[:profile]
       redirect_to person_path(params[:profile])
diff --git a/config/locales/diaspora/en.yml b/config/locales/diaspora/en.yml
index 431a83c7e..d63e1ec40 100644
--- a/config/locales/diaspora/en.yml
+++ b/config/locales/diaspora/en.yml
@@ -345,6 +345,7 @@ en:
     create:
       sent: "Message sent"
       fail: "Invalid message"
+      no_contact: "Hey, you need to add the contact first!"
     new_message:
       fail: "Invalid message"
     destroy:
diff --git a/spec/controllers/conversations_controller_spec.rb b/spec/controllers/conversations_controller_spec.rb
index ef4cdd86a..a0963bcf8 100644
--- a/spec/controllers/conversations_controller_spec.rb
+++ b/spec/controllers/conversations_controller_spec.rb
@@ -113,6 +113,30 @@ describe ConversationsController do
       end
     end
 
+    context 'with empty subject' do
+      before do
+        @hash = {
+          :conversation => {
+            :subject => ' ',
+            :text => 'text debug'
+          },
+          :contact_ids => [alice.contacts.first.id]
+        }
+      end
+
+      it 'creates a conversation' do
+        lambda {
+          post :create, @hash
+        }.should change(Conversation, :count).by(1)
+      end
+
+      it 'creates a message' do
+        lambda {
+          post :create, @hash
+        }.should change(Message, :count).by(1)
+      end
+    end
+
     context 'with empty text' do
       before do
         @hash = {
@@ -136,6 +160,30 @@ describe ConversationsController do
         }.should_not change(Message, :count).by(1)
       end
     end
+
+    context 'with empty contact' do
+      before do
+        @hash = {
+          :conversation => {
+            :subject => 'secret stuff',
+            :text => 'text debug'
+          },
+          :contact_ids => ' '
+        }
+      end
+
+      it 'does not create a conversation' do
+        lambda {
+          post :create, @hash
+        }.should_not change(Conversation, :count).by(1)
+      end
+
+      it 'does not create a message' do
+        lambda {
+          post :create, @hash
+        }.should_not change(Message, :count).by(1)
+      end
+    end
   end
 
   describe '#show' do