Unzip a mail attachment

Question

The following line gives problems

content = new StreamReader(new GZipStream(new MemoryStream(a.RawBytes), CompressionMode.Decompress)).ReadToEnd();

InvalidDataException occurred: The magic number in GZip header is not correct. Make sure you are in a GZip stream.

can I not convert the attachment to a byte array or what am I doing wrong?

Attachment a = (from x in mail.Attachments.OfType<Attachment>()
   where !string.IsNullOrEmpty(x.Body) || x.RawBytes != null
   select x).FirstOrDefault();

AttachmentName = a.Name;
string AttachmentType = a.Name.Substring(a.Name.Length - 3, 3).ToUpper();

switch (AttachmentType)
{
   case "ZIP":
      content = new StreamReader(new GZipStream(new MemoryStream(a.RawBytes), CompressionMode.Decompress)).ReadToEnd();
      break;
   default:
      content = new StreamReader(new MemoryStream(a.RawBytes)).ReadToEnd();
      break;
}

Answer 1

A GZip file is not the same thing as a Zip file. You want System.IO.Compression.ZipFile or ZipArchive.