Invitation message are generated by blogger.com and look something like this:
From: Bob Goudreau [mailto:firstname.lastname@example.org]
Sent: Saturday, January 19, 2008 5:54 PM
Subject: You have been invited to contribute to Bob Goudreau's blog
The Blogger user Bob Goudreau has invited you to contribute to the blog: Tarheel Swimming Association Blog.
To contribute to this blog, visit:
You'll need to sign in with a Google Account to confirm the invitation and start posting to this blog. If you don't have a Google Account yet, we'll show you how to get one in minutes.
To learn more about Blogger and starting your own free blog visit http://www.blogger.com.