It is no surprise that your actual voice mail greeting must be delivered in the same way: Professional, clear, brief, and to the point. In a previous blog, "Marketing Messages on Your Cell Say You Mean Business," some techniques for making a professional voice mail greeting were discussed. There are many similarities between leaving a voice mail, and producing a voice mail greeting. You want your callers and receivers to hear a confident and professional person on the other end delivering a coherent message. You should introduce yourself to a prospective client in a personal way. An email doesn't generate much discussion, nor does it necessarily show you went the extra mile in contacting the client. Generating conversation. A professional, well conveyed voice message shows the voice mail receiver that you are confident and well-spoken, and that there is a person behind the message. Emails can be prepared, edited, and revised unlike voice mail messages An email or email chain thread is documentation of a conversation that can easily be referenced In an email you can include a phone number, address, website, etc that may be hard to remember or record through voice mail communication Emails can be forwarded, CC'ed, and blasted.
Here's an advanced technique for all you overachievers. It's "advanced" because it's rarely used, not because it's difficult. The trick? Leave two sales voicemails instead of one. Let us explain:

We've all heard that automated voice mail lady, telling us what to do after the beep. But fewer people than ever are leaving messages. And the millennials, they won't even listen to them — they'd much rather receive a text or Facebook message.
Unopened: Messages of which you have listened to the headers, but not the message itself.