system.net.mail not working after server migration

I really have big problems with my CMS-system on EasyCgi. They just changed server and after the migration I can only use system.web.mail  and not system.net.mail.

I have a file called errormail.aspx, sending a email to me if there occurs some errors on the site.
 Sub errormail(strSubject as string, strErrormessage as string)
Dim sender As new System.Net.Mail.MailAddress("fejl@mydomain.com")
Dim recipient As new System.Net.Mail.MailAddress(myname@myemail.com)
Dim msg As New System.Net.Mail.MailMessage(sender,recipient)
msg.Subject = strSubject
msg.Body = strErrormessage
Dim client As New Syst ...