.ASP email send returning 500 - Internal server error IIS

I've copied some pages from our old server to a new one, this page is no longer sending emails and instead is throwing an error.  I expect I haven't set something right with the server/service since it worked before and the code hasn't changed.  Here's the sub that's dieing:

sub send_email(x_subject, x_body, x_to, x_from)
'used for sending mail to a single recipient
      sch = "http://schemas.microsoft.com/cdo/configuration/" 
    set cdoConfig = CreateObject("CDO.Configuration")
    with cdoConfig.Fields
        .Item(sch & "sendusing") = 2
            .Item(sch & "smtpserver") = "127.0.0.1"
        .update
    end with

    set cdoMessage = CreateObject("CDO.Message")  
    with cdoMessage
        set .Configuration = cdoConfig
        .From = x_from
            .To = x_to
        .Subject = x_subject
        .HtmlBody = x_body
        .Send
    end with
 
    set cdoMessage = nothing  
    set cdoConfig = nothing
end sub

If I comment out the call to the sub there's no error, but it also doesn't send the email, obviously.