The syntax for returning the line number of the ASP error using the GetLastError object is :
set objError = Server.GetLastError()
strErrorLine = objError.Line
Note though that you cannot use this in your standard asp application pages and expect it to work. You need to modify the default error page (500-100.asp) which handles ASP error reporting and displays the results on the screen. To get the error emailed to you you can replace this page with your own version which will display a custom message to the user and then email the error report to you.