This e-mail is to announce to close friends and relatives that you're getting married.
Sometime in the next few months you'll be getting a really fancy invitation in "snail mail." But before that I wanted you to be one of the first to know: <fiancee's name> and I are getting married! Can you believe it? <brief description of proposal>. Needless to say, the families are <descriptions of families' feelings> and we're already starting the planning. It's going to be a lot of work, but worth it. Promise me one thing: don't tell anybody for a while. I haven't e-mailed everyone yet, and I don't want to spoil the surprise. So please wait <time to keep wedding a secret> OK? Then you can go ahead and tell the world! I'll tell you more next time I talk to you. Take care!