DecodeWords data not handled correctly in some cases about s22.imap HOT 1 CLOSED

        public string Name {
            get { 
                return name;
            } 
            set { 
                Encoding nameEncoding = MimeBasePart.DecodeEncoding(value);
                if(nameEncoding != null){ 
                    this.nameEncoding = nameEncoding;
                    this.name = MimeBasePart.DecodeHeaderValue(value);
                    MimePart.ContentType.Name = value;
                } 
                else{
                    this.name = value; 
                    SetContentTypeName(); 
                }
            } 
        }

internal class MimeBasePart 
    {
....
        internal static Encoding DecodeEncoding(string value) { 
            if(value == null || value.Length == 0){
                return null; 
            } 

            string[] subStrings = value.Split('?'); 
            if ((subStrings.Length != 5 || subStrings[0] != "=" || subStrings[4] != "=")) {
                return null;
            }
            string charSet = subStrings[1]; 
            return Encoding.GetEncoding(charSet);
        } 

            if (String.IsNullOrEmpty(name) && part.Parameters.ContainsKey("name"))
                name = Util.DecodeWords(part.Parameters["name"]);