Test your EMail settings first. You may wish to consider this mod. As for the content of those messages, look at lines 752-777 in "register.asp".
Sorry, I was brain dead when I wrote this. This is for auto EMail validation. Instead, see below for EMail content. Please post a link to your "admin_accounts_pending.asp" in .txt format for us to check.
"admin_accounts_pending.asp"