Regarding the smartness question -- there is a group of settings (shown in the extended mode) to trigger mail sync based on events, like WiFi or mobile becoming connected, or the device's "master switch" for background sync getting enabled.
As far as alarms go -- it's hard to get the execution paths down to absolute minimum for every combination of settings.
Right now, what you're seeing is that, the app wakes up on the usual background sync schedule, discovers there is no network connection, and lets the device go back to sleep.
Where does it stand in the device's standard battery consumption screen?