Originally Posted by tsac
Not sure you can single out a message that is sent for voice mail in the email section. Mine is sent as an email message and I have never found a way to select it from other emails. If you get a call and it's only from a single number you may be able to set it to a special ring tone.
Is it actually an email or an SMS? Most voicemail systems that I've used that don't properly support the message waiting indicator rely on SMS for notification. If that's the case, setting a different alert for SMS in Profiles would work.
It looks like even though my carrier does support MWI that the voicemail alert is the same as the SMS alert.