Delphi XE5: Problems with proper visualization of extracted GMail emails - email

Question

I am facing some trouble in properly visualizing emails extracted from GMail. I use the GMail API to retrieve the messages. This part seems to be working properly and I get the json with the entire message.
Here is a small part of one of the body parts
"mimeType": "multipart/alternative",
"filename": "",
"headers": [
{
"name": "Content-Type",
"value": "multipart/alternative; boundary=001a114710d029267205278f13b9"
}
],
"body": {
"size": 0
},
"parts": [
{
{
"partId": "0.0",
"mimeType": "text/plain",
"filename": "",
"headers": [
{
"name": "Content-Type",
"value": "text/plain; charset=UTF-8"
},
{
"name": "Content-Transfer-Encoding",
"value": "quoted-printable"
}
],
"body": {
"size": 549,
"data": "SGkgUGF1bCwNCg0KQXBvbG9naWVzLCBidXQgSSBmb3Jnb3QgdG8gbWVudGlvbiB0aGF0IHRoZSByZXN0IG9mIHlvdXIgb3JkZXIgaGFzIGJlZW4NCnNlbnQgb3V0IGluIHRoZSBtZWFudGltZQ0KDQpNYW55IHRoYW5rcw0KDQoqS2luZCBSZWdhcmRzKg0KKkJhcmJhcmEgSm9uZXMqDQoqSW50ZXJuZXQgU2FsZXMqDQoNCipPbGQgTWlsbCBTYWRkbGVyeSoNCg0KKnd3dy5zYWRkbGVyeS5iaXogPGh0dHA6Ly93d3cuc2FkZGxlcnkuYml6Lz4qDQoNCipUZWw6ICs0NCAoMCkyOCA5MzM1IDMyNjggPCUyQjQ0JTIwJTI4MCUyOTI4JTIwOTMzNSUyMDMyNjg-Kg0KDQoqVGFrZSBhIFZpcnR1YWwgdG91ciBvZiBvdXIgc2hvcCoNCkdvb2dsZSBwbGFjZXMgaHR0cDovL2dvby5nbC85Y1o5ZDANCipbaW1hZ2U6IElubGluZSBpbWFnZXMgNF1XaXNoaW5nIHlvdSBhIHZlcnnigItbaW1hZ2U6IElubGluZSBpbWFnZXMgM10qDQoqICAgICAgICAgICAgICAgICAgTWVycnkgQ2hyaXN0bWFzKg0KDQoq4oCLICAg4oCLICDigIsgICAgW2ltYWdlOiBJbmxpbmUgaW1hZ2VzIDJd4oCLKg0K"
}
}
So what is the data part encoded with? I am getting confused with the "Content-Transfer-Encoding" ->"quoted-printable". Should I decode the value of the data using a "quoted-printable" decoder or not?
Initially without noticing the "quoted-printable" value, I decoded the data value using DecodeBase64, here is how I am making it
function TViewEmailsForm.DecodeData(aStr: String): String;
var
aStrm: TBytesStream;
aStrStrm: TStringStream;
begin
Result := '';
if aStr = '' then
Exit;
aStrm := TBytesStream.Create(DecodeBase64(aStr));
aStrStrm := TStringStream.Create;
try
aStrm.Position := 0;
aStrStrm.LoadFromStream(aStrm);
Result := aStrStrm.DataString;
finally
aStrm.Free;
aStrStrm.Free;
end;
end;
Using that returns human readable text, however at the end something more is decoded and I don't get what it is. I presume it is some kind of formatting bold text, link, kind of signature but I don't succeed in anyway to show it properly (not sure what to use though as component - RichEdit, HTMLViewer)
The end of the decoded string looks like
.......
*Name of the company*
*website of the company <again the website of the company>*
*Tel: [phone] <%2B44%20%280%2928%209335%203268
ѓBѓBЉ•ZЩHHљ\ќX[Э\€Щ€Э\€ЪЬ
ѓB‘ЫЫЩЫHXЩ\И‹ЛЩЫЫЛ™ЫОXЦЋYBЉ–Ъ[XYЩN€[›[™H[XYЩ\И
UЪ\Ъ[™И[ЭHH™\ћx "ЦЪ[XYЩN€[›[™H[XYЩ\ИЧJѓBЉ€Y\њћHЪљ\ЭX\КѓBѓBЉё "И8 "И8 "ИЪ[XYЩN€[›[™H[XYЩ\И—x "КѓB›
I have some other messages which pretend to have html body, but again the data is seen in that way. I tried to load this string into the lines of TRichEdit, but had no luck, I tried to use TIdDecoderQuotedPrintable to decode this string, though I am not sure if I have to make it, but some of the characters got replaced by '?' (question marks)
What I am missing here and what is the proper way of visualizing the content of the messages?

Answer 1

After serious research and testing different encoders/decoders I finally managed to properly decode what was encoded in the message.
I used Indy's TIdEncoderMIME found in IdCoderMIME and used the DecodeString method. The HTML messages and bodies are properly decoded too with it.
Hope this will help other people not to spend two days in "fighting" with decoding messages!
EDIT: I noticed that the symbol > comes as ? Maybe there something else which has to be done?
EDIT2: It seems that the encoding of the data is not actually Base64 but Base64Url. On the following link http://blog.marcocantu.com/blog/delphi_facebook_base64_encoding.html you can find interesting post on that. The images are encoded in that way and the standard decoding doesn't work for extracting them.
Whoever knows French can read something here too http://codes-sources.commentcamarche.net/source/51156-base64-base64url-encode-decode