public static class Parser
	{		
		public static string FromMixedEncoding(string message)
		{
			// =?koi8-r?B?Rlc6IPrBzcXOwSDczMXL1NLJ3sXTy8nIIMzBzdA=?=    =?koi8-r?B?+sHNxc7BINzMxcvU0snexdPLycggzMHN0A==?=   fdsfds

			return Regex.Replace (
				message,
				@"(?<entry>=\?(?<charset>[\-\w]+)\?(?<encoding>[bq])\?(?<data>.+?)\?=)",
				match => {
					try {
						string encoding = match.Groups ["encoding"].Value;
						string charset = match.Groups ["charset"].Value;
						string data = match.Groups ["data"].Value;

						return Encoding
							.GetEncoding (charset)
							.GetString (
								encoding.Equals("b", StringComparison.InvariantCultureIgnoreCase) 
						            ? FromBase64Encoding(data) 
						            : FromQuotedPrintableEncoding (data));
					}
					catch {
						return "ERROR_OF_PARSING";
					}
				},
				RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
		}

        public static byte[] FromQuotedPrintableEncoding(string text)
        {
			//=20
			//
			//=20
			//
			//From: =E4=C9=D3=D0=C5=D4=DE=C5=D2=D3=CB=C9=CA =D0=D5=CE=CB=D4 =
			//=F5=D0=D2=C1=D7=CC=C5=CE=C9=D1 =C4=C5=CC=C1=CD=C9=20
			//Sent: Tuesday, May 19, 2009 3:18 PM
			//To: =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =D7 =
			//=ED=CF=D3=CB=D7=C5; =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =D7 =
			//=ED=CF=D3=CB=D7=C5 2; =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =
			//=ED=CF=D3=CB=CF=D7=D3=CB=CF=CA =CF=C2=CC=C1=D3=D4=C9
			//Subject: FW: =FA=C1=CD=C5=CE=C1 =DC=CC=C5=CB=D4=D2=C9=DE=C5=D3=CB=C9=C8 =
			//=CC=C1=CD=D0
			//
			//=20
			//
			//=20
			//
			//=20

			// removing hidden characters	
            text = text.Replace("=\r\n", "");

            using (var stream = new MemoryStream(text.Length))
            {
                int currentPos = 0;
                while (true)
                {
                    if (currentPos >= text.Length)
                        break;

                    var currentChar = text[currentPos];
                    switch (currentChar)
                    {
                        case '=':
                            stream.WriteByte(Convert.ToByte(text.Substring(currentPos + 1, 2), 16));
                            currentPos += 3;
                            break;
                        default:
                            stream.WriteByte(Convert.ToByte(currentChar));
                            currentPos += 1;
                            break;
                    }
                }

                return stream.ToArray();
            }
        }

		public static string FromQuotedPrintableEncoding(string text, string charset)
		{
			//=20
			//
			//=20
			//
			//From: =E4=C9=D3=D0=C5=D4=DE=C5=D2=D3=CB=C9=CA =D0=D5=CE=CB=D4 =
			//=F5=D0=D2=C1=D7=CC=C5=CE=C9=D1 =C4=C5=CC=C1=CD=C9=20
			//Sent: Tuesday, May 19, 2009 3:18 PM
			//To: =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =D7 =
			//=ED=CF=D3=CB=D7=C5; =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =D7 =
			//=ED=CF=D3=CB=D7=C5 2; =F7=D3=C5 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=C9 =
			//=ED=CF=D3=CB=CF=D7=D3=CB=CF=CA =CF=C2=CC=C1=D3=D4=C9
			//Subject: FW: =FA=C1=CD=C5=CE=C1 =DC=CC=C5=CB=D4=D2=C9=DE=C5=D3=CB=C9=C8 =
			//=CC=C1=CD=D0
			//
			//=20
			//
			//=20
			//
			//=20

			return Regex.Replace(
				text.Replace("=\r\n", ""), 			// removing hidden characters				
				@"=(?<hex>\w{2})", 					// taking hex-codes from the text
				match => Encoding					// replacing hex-codes their char values in needed charset
							.GetEncoding(charset)
							.GetString(new byte[] {
								Convert.ToByte(match.Groups["hex"].Value, 16)	// converting hex to byte
							}), 
				RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.Multiline | RegexOptions.IgnoreCase);
		}

        public static byte[] FromBase64Encoding(string text)
        {
            return Convert.FromBase64String(text);
        }

        public static string GetTextWithoutQuotes(string text)
        {
            return text.Trim(new[] {'"'});
        }

        public static byte[] From8BitEncoding(int codepage, string text)
        {
            return Encoding.GetEncoding(codepage).GetBytes(text);
        }

		public static byte[] From8BitEncoding(string charset, string text)
        {
            return Encoding.GetEncoding(charset).GetBytes(text);
        }
    }