diff --git a/application/classes/Model/Course.php b/application/classes/Model/Course.php
index db52b82..29ce5fb 100644
--- a/application/classes/Model/Course.php
+++ b/application/classes/Model/Course.php
@@ -111,7 +111,24 @@ class Model_Course extends ORM {
    **/
   public static function get_ids()
   {
-    return DB::select('course_id')->distinct(TRUE)->from('clients_courses')->execute()->as_array(NULL, 'course_id');
+    $use_groups = Kohana::$config->load('common.groupmode');
+    if( ! $use_groups)
+    {
+      return DB::select('course_id')
+        ->distinct(TRUE)
+        ->from('clients_courses')
+        ->execute()
+        ->as_array(NULL, 'course_id');
+    }
+    else
+    {
+      $groups = Model_Group::get_ids();
+      return DB::select('id')
+        ->from('courses')
+        ->where('group_id', 'IN', $groups)
+        ->execute()
+        ->as_array(NULL, 'id');
+    }
   }
 
   public static function get_period($course_id)
@@ -130,13 +147,31 @@ class Model_Course extends ORM {
       ->order_by('order');
     return $query->execute()->as_array(NULL, 'id');
   }
+
   public static function get_client_ids($course_id)
   {
-    return DB::select('client_id')
-      ->from('clients_courses')
-      ->where('course_id', '=', $course_id)
-      ->execute()
-      ->get('client_id');
+    $use_groups = Kohana::$config->load('common.groupmode');
+    if( ! $use_groups)
+    {
+      return DB::select('client_id')
+        ->from('clients_courses')
+        ->where('course_id', '=', $course_id)
+        ->execute()
+        ->get('client_id');
+    }
+    else
+    {
+      $group_id = DB::select('group_id')
+        ->from('courses')
+        ->where('id', '=', $course_id)
+        ->execute()
+        ->get('group_id');
+      return DB::select('client_id')
+        ->from('clients_groups')
+        ->where('group_id', '=', $group_id)
+        ->execute()
+        ->get('client_id');
+    }
   }
 
   /**
diff --git a/application/classes/Model/Group.php b/application/classes/Model/Group.php
index 88c9027..b496c11 100644
--- a/application/classes/Model/Group.php
+++ b/application/classes/Model/Group.php
@@ -48,4 +48,12 @@ class Model_Group extends ORM {
   {
     return self::count($this->id);
   }
+
+  /**
+   * Get ID of all groups which have subscribers
+   **/
+  public static function get_ids()
+  {
+    return DB::select('group_id')->distinct(TRUE)->from('clients_groups')->execute()->as_array(NULL, 'group_id');
+  }
 }
diff --git a/application/classes/Task/Prepare.php b/application/classes/Task/Prepare.php
index f2853d8..659430d 100644
--- a/application/classes/Task/Prepare.php
+++ b/application/classes/Task/Prepare.php
@@ -17,10 +17,12 @@ class Task_Prepare extends Minion_Task
     if (is_null($course))
     {
       Log::instance()->add(Log::ERROR, 'Course ID is NULL when preparing');
+      echo "Course ID is NULL when preparing\n";
       return;
     }
     $count = Model_Course::count_letters($course);
     if ($count == 0)
+      echo "No letters found in course $course; skipping.\n";
       return;
     $period = Model_Course::get_period($course);
     $clients = Model_Course::get_client_ids($course, $period);
@@ -46,6 +48,8 @@ class Task_Prepare extends Minion_Task
       if ($letter !== FALSE)
       {
         Model_Task::prepare($client_id, $letter);
+      } else {
+        echo "No letters to prepare.\n";
       }
     } else {
       echo "Letter won't be prepared because it's too early to send it.\n";
@@ -83,6 +87,8 @@ class Task_Prepare extends Minion_Task
     }
     catch(Database_Exception $e)
     {
+      echo $e->getMessage();
+      Log::instance()->add(Log::ERROR, $e->getMessage());
       $db->rollback();
     }
   }
diff --git a/application/tests/CoursesTest.php b/application/tests/CoursesTest.php
index 2f9a8e4..b28322d 100644
--- a/application/tests/CoursesTest.php
+++ b/application/tests/CoursesTest.php
@@ -15,6 +15,20 @@ class CoursesTest extends Unittest_Database_TestCase
     return $this->createXMLDataSet(Kohana::find_file('tests', 'test_data/courses', 'xml'));
   }
 
+  function test_get_ids()
+  {
+    $courses = Model_Course::get_ids();
+    $this->assertNotEmpty($courses);
+    $this->assertContains(1, $courses);
+  }
+
+  function test_get_clients()
+  {
+    $clients = Model_Course::get_client_ids(1);
+    $this->assertNotEmpty($clients);
+    $this->assertContains('1', $clients);
+  }
+
   /**
    * @group Mail
    **/
diff --git a/application/tests/test_data/courses.xml b/application/tests/test_data/courses.xml
index 03bd0e8..846c775 100644
--- a/application/tests/test_data/courses.xml
+++ b/application/tests/test_data/courses.xml
@@ -1,17 +1,27 @@
 <?xml version="1.0" ?>
 <dataset>
+  <table name="groups">
+    <column>id</column>
+    <column>name</column>
+    <row>
+      <value>1</value>
+      <value>Test Group</value>
+    </row>
+  </table>
   <table name="courses">
     <column>id</column>
     <column>title</column>
     <column>description</column>
     <column>period</column>
     <column>price</column>
+    <column>group_id</column>
     <row>
       <value>1</value>
       <value>Test course</value>
       <value>Application testing purposes</value>
       <value>1</value>
       <value>0</value>
+      <value>1</value>
     </row>
   </table>
   <table name="clients">
@@ -36,6 +46,11 @@
       <value>1</value>
     </row>
   </table>
+  <table name="clients_groups">
+    <column>id</column>
+    <column>client_id</column>
+    <column>group_id</column>
+  </table>
   <table name="letters">
     <column>id</column>
     <column>text</column>