If you have favored voice message rather than normal text email, Blind Speak is a good option for you. This service synthesizes the text, provided by you, into MP3 and allows you to send it as an attachment over email. You get a preview of how the output will look like with an option to choose a male or female voice.
This service you might not use normally but could be useful for people who are blind, they can hear the message instead of using anything else to read out the email you sent.
Check out Blind Speak