diff --git a/addons/mail/data/mail_data.xml b/addons/mail/data/mail_data.xml
index 3f517ee7858..02cfd626768 100644
--- a/addons/mail/data/mail_data.xml
+++ b/addons/mail/data/mail_data.xml
@@ -27,6 +27,19 @@
             <field name="priority">1000</field>
         </record>
 
+        <record id="ir_cron_mail_garbage_collect_attachments" model="ir.cron">
+            <field name="name">Garbage Collect Mail Attachments</field>
+            <field eval="True" name="active" />
+            <field name="user_id" ref="base.user_root" />
+            <field name="interval_number">1</field>
+            <field name="interval_type">weeks</field>
+            <field name="numbercall">-1</field>
+            <field eval="False" name="doall" />
+            <field name="model">mail.thread</field>
+            <field name="function">_garbage_collect_attachments</field>
+            <field name="args">()</field>
+        </record>
+
         <!-- Discussion subtype for messaging / Chatter -->
         <record id="mt_comment" model="mail.message.subtype">
             <field name="name">Discussions</field>
diff --git a/addons/mail/mail_thread.py b/addons/mail/mail_thread.py
index 173ec951b32..2d43b93dd9a 100644
--- a/addons/mail/mail_thread.py
+++ b/addons/mail/mail_thread.py
@@ -389,6 +389,26 @@ class mail_thread(osv.AbstractModel):
             return [('message_unread', '=', True)]
         return []
 
+    def _garbage_collect_attachments(self, cr, uid, context=None):
+        """ Garbage collect lost mail attachments. Those are attachments
+            - linked to res_model 'mail.compose.message', the composer wizard
+            - with res_id 0, because they were created outside of an existing
+                wizard (typically user input through Chatter or reports
+                created on-the-fly by the templates)
+            - unused since at least one day (create_date and write_date)
+        """
+        limit_date = datetime.datetime.utcnow() - datetime.timedelta(days=1)
+        limit_date_str = datetime.datetime.strftime(limit_date, tools.DEFAULT_SERVER_DATETIME_FORMAT)
+        ir_attachment_obj = self.pool.get('ir.attachment')
+        attach_ids = ir_attachment_obj.search(cr, uid, [
+                            ('res_model', '=', 'mail.compose.message'),
+                            ('res_id', '=', 0),
+                            ('create_date', '<', limit_date_str),
+                            ('write_date', '<', limit_date_str),
+                            ], context=context)
+        ir_attachment_obj.unlink(cr, uid, attach_ids, context=context)
+        return True
+
     #------------------------------------------------------
     # Email specific
     #------------------------------------------------------