Assigned task mail not received!

When a task is assigned to an user he or she receives always a notification e-mail immediately. Well, always not. If the user has synchronized the tasks list with Outlook 2007 the e-mail will not be sent and he will receive the notification in his task pane.

SharePoint Designer workflows and enabled incoming mail lists

This week I created a workflow which starts automatically on event added. All works fine if I add the items manually but if I email the items to the list the workflow does not start. The reasons:

- Security restriction: From SP1 there is a security fix that avoid starting a workflow by the system account identity. Changing the identity of application pool to a non-system account will fix the problem.
http://support.microsoft.com/kb/947284/

- Incoming mail: In addition to the previous problem, you need to explicitly allow the farm to start a workflow when a new item is created by mail. To do it you need SP1 + Infrastructure Update (or SP2) and execute the following command:
stsadm -o - pn declarativeworkflowautostartonemailenabled - setproperty va true
http://support.microsoft.com/kb/953289/