public void NameEncoding()
{
Attachment attach = Attachment.CreateAttachmentFromString("test", "attachment-name");
Assert.Null(attach.NameEncoding);
Attachment a = new Attachment(new MemoryStream(), "myname");
Assert.Null(a.NameEncoding);
a = new Attachment(new MemoryStream(), "myname\u3067");
Assert.Null(a.NameEncoding);
}