yes there is a way to do it. It's not an Apple feature. It is done through Sprint. It will change the way your voicemail works however.
Turn on the Sprint exclusive Google Voice integration at Google.com/voice/sprint (option 1).
Google voice will give you a lot of controls, including emailing you about voicemail.
You'll record your greeting at the google voice website. On your iPhone you'll download the Google Voice app. That app is now how you will see/listen/read voicemail and free voicemail transcriptions -- you still get visual voicemail.