Maybe you’re looking at a system error. But I doubt that.
Look at how chintzy FB is now - they will prevent you from sending your e-mail address in a message. Just to try and keep you hooked make you work another way around it. Never mind charging you a dollar to send a message to a stranger, now they won’t let you talk to your friends there. Facebook thinks that you won’t find a work around, but it is offensive to be treated like an idiot like this.
If anyone from Facebook cares to comment or correct me and confirm that they do allow people to send e-mail addresses in personal messages, you have 45 days from the date of publication of this post to do it; just add a Disqus comment.