问MailMessage依附于byte[]

EN

public static class StreamExtensions
{
    public static byte[] ReadAllBytes(this Stream instream)
    {
        if (instream is MemoryStream)
            return ((MemoryStream) instream).ToArray();

        using (var memoryStream = new MemoryStream())
        {
            instream.CopyTo(memoryStream);
            return memoryStream.ToArray();
        }
    }
}

System.Net.Mail.MailMessage m = new MailMessage();
foreach (var element in m.Attachments)
{
  byte[] bytes = element.ContentStream.ReadAllBytes()
   element.ContentType // you will want to save this as well so you can convert it to a file when you need to pull it back out of the database.
}