Hi.
I'm not sure what device type you're talking about, but if it's SNMP capable, most IOS devices support traps on failed logins, or if that's not supported, and syslogging is, the device (again, if running IOS) can send a syslog trap for the failed login attempt to a NMS server that supports email notification of events (such as Ciscoworks (LMS)-Device Fault Manager).
Is this the kind of thing you're looking for?
HTH,
-Joe