If you are using .NET to write a program to send e-mail by using System.Web.Mail and SMTPMail, you may encounter the error message:

SMTP error: Could not access CDO.Message object

when trying to send this e-mail. The problem is because of the line:

SMTPMail.SMTPServer = "your.mail.relay"

Please note the SMTP Server you are try to use, your.email.relay, may not want to replay you. Even this server is localhost:

SMTPMail.SMTPServer = "localhost"

Please be sure 127.0.0.1 is listed in the relay list of that SMTP Server.