If he's doing delivery he's going to be using his hands alot and a flashlight might be problematic. Have you considered a headlamp instead?
There are several good options out there, particularly Zebralights and Fenixes. I'd say get him a Zebralight H50. Comes with a very nice head strap and a glow in the dark holder/bracket for the strap, runs on readily available AA batteries, and if you use disposable Energizer L91's in it is feather weight and will run for a very long time. You also have the option of using Nimh's in it and alkalines in a pinch. All versions of the H50 are on sale on ZebraLight's website right now and any of them can be had for $47 - $49 and they don't charge for shipping. I'd recommend the H50w. If he's going to be walking down long driveways or the like, then an H51 would be the better choice. It's more expensive, although it will be brighter, throw a beam a MUCH greater distance, and more versatile because it has more output settings.
Another good and inexpensive option is a Photon Freedom or Micro. They can live on a keychain and have an optional clip accessory to put them on the bill of a cap or the like to work as a headlamp. They won't be nearly as bright as a true dedicated headlamp though, so might be useful for backup duty on a keychain for when the battery in your main headlamp goes out unexpectedly. They are also available in multiple colors and can be used for signaling too if needed. I keep one in my cycling bag and use it when I'm off the bike and need just a small amount of light around me for seeing what I'm doing.