Symptoms

Query regarding Out Of Office and destination users - When a task is assigned to a user that is "Out Of Office", the task is delegated to the configured users, but the delegated users don't receive the task email notification. Is this correct or is a bug? For us it is mandatory the notification for delegate users.
 

Diagnoses

This comes down to the destination users. When OOF is set, the destination user doesn't change.
 

Resolution

What you are experiencing is the normal intended behavior of out of office. The reason behind this behavior is that notifications are sent to the destination user(s) of a task only. The secondary user is simply delegated permission to access and action the task item. The ownership of the task still flows to the original destination user, which does not change based on Out of Office rules.

One suggestion that has worked previously in this situation is coupling K2's Out of Office function with Outlook/Exchange Out of Office to forward messages to the relevant user.