A technique for handling interrupts in a data processing system includes receiving, by an interrupt routing controller (IRC), an event routing message (ERM) that includes an event source number for a notification source with an unserviced interrupt. In response to receiving the ERM, the IRC builds an event notification message (ENM) based on the event source number. The IRC determines a scope for the ENM based on an event target group (ETG) associated with the event source number. The IRC issues the ENM to an interrupt presentation controller (IPC) at the scope associated with the ETG.