Resolve asp mail issue on Windows server

Site has forms created in classic ASP (note: classic ASP, NOT ASP.net), just moved to a new server and emails generated by site forms do not work. Using CDO for mail sending, but it keeps generating SMTP errors. All forms call a [login to view URL] file that specifies mailing parameters, but apparently there's something not quite right in it. Site hosting company not much assistance, says get a coder to help. Need this done quickly, client who owns site getting testy.