CDO (Collaboration Data Objects) is deprecated and intended only for legacy Classic ASP applications running on Windows Server with IIS. For modern applications, SMTP libraries or API-based mail services are strongly recommended.

Sample legacy code for sending email using CDO with authenticated SMTP.

Const cdoSendUsingPort = 2
Const cdoBasic = 1

Set objMessage = Server.CreateObject("CDO.Message")
objMessage.Subject = "Example CDO Message"
objMessage.From = "me@your-domain-name.com"
objMessage.To = "recipient@example.com"
objMessage.TextBody = "This is a sample message." & vbCRLF & "Sent using authenticated SMTP."

With objMessage.Configuration.Fields
.Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = cdoSendUsingPort
.Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "mail.your-domain-name.com"
.Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = cdoBasic
.Item("http://schemas.microsoft.com/cdo/configuration/sendusername") = "me@your-domain-name.com"
.Item("http://schemas.microsoft.com/cdo/configuration/sendpassword") = "yourpassword"
.Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 587
.Item("http://schemas.microsoft.com/cdo/configuration/smtpusessl") = True
.Update
End With

objMessage.Send