Hi Claudio,
I don't know Cassini, we have (and use) Merak mail server on our web server (which is IIS), and in code we had to specify the SmtpServer to the valid smtp server (which is the server itself) just before send the email.

System.Web.Mail.SmtpMail.SmtpServer = ConfigurationSettings.AppSettings.Item("smtpserver").ToString()
System.Web.Mail.SmtpMail.Send(msg)

the smtpserver key in web.config is usually "localhost" when in development (where smtp is IIS), and "mail.thedomain.xx" when on the server (where SMTP is managed by Merak).
Also maybe you can have security issue (the smtp server must allow send mail that are coming from the machine itself)

HTH

Franco

>Hi all,
>
>we're building a web app here (ASP.NET 2.0) and using the file system web server (cassini). We have some functionality in there to send out some emails. When we started this project, we were using IIS, and eventually switched to Cassini. When we were using IIS, the code that sends emails through smtp used to work fine, but it just quit working after we switched to using Cassini.
>
>Any ideas there?