Sending Attachment With Mail

I use the following code to attach a file to my mail

Dim objMail
Set objMail = Server.CreateObject("CDONTS.NewMail")
objMail.From = Request("email")
objMail.Subject = "subject"objMail.AttachFile Server.MapPath("./Uploads/"&file_name)

objMail.To = "xyz@xyz.com"
objMail.MailFormat = 0
objMail.BodyFormat = 0
strBody="hai"
objMail.Body = strBody
objMail.Send


I attach files from the folder uploads which r uploaded there by the user. The problem is that when i recieve the attachment i get a .dat extension with it for eg ;if i attach a.txt i recieve a.txt.dat....