[1.0/1.1] Smtp Mail Attachments

[Jumpercables]

I'm trying to send an attachment using smtp. I have been successful in sending emails without attachments but every thing I have tried when using the MailAttachment object results in Invalid Attachment.

I know the attachment exists and that I have access to the file. I have tried both MailEncoding's but with the same result.

Any ideas?

MailMessage mailMessage = new MailMessage();
mailMessage.Attachments.Add( new MailAttachment(temp, MailEncoding.UUEncode));
mailMessage.From = txtTo.Text
mailMessage.To = txtEmail.Text;
mailMessage.Subject = "Attachment"
mailMessage.Body = "Attachment Test";

SmtpMail.Server = "localhost";
SmtpMail.Send(mailMessage);