System.Net.Mail.MailMessage TransferEncoding

[Gerald S.]

MailMessage message = new MailMessage(from, to);
message.Body = "Message body";
message.BodyEncoding = System.Text.Encoding.UTF8;
message.Subject = "Subject";
message.SubjectEncoding = System.Text.Encoding.UTF8;

When the above message is sent, it's encoded by default with "base64",
according to
http://msdn2.microsoft.com/system.net.mail.mailmessage.bodyencoding.aspx.

Now I'd like to have the message encoded with "quoted-printable". Is there
any way to achieve this?

For example, Outlook Express uses quoted-printable with utf-8 by default.
Why can't I set TransferEncoding for the message body in ASP.NET 2.0?

Thanks
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