How to send base64Url encoded Raw Email message?

I got Gmail RFC 2822 compliant message which contains everything (headers,body,subject etc.). The message is base64url encoded. I am trying to parse this message and send it to Exchange online. So far I have tried Sasa Mime library but this great library doesn't work for me.

string strRaw = System.IO.File.ReadAllText(@"G:\raw.txt");
var mail = Sasa.Net.Mail.Message.Parse(strRaw);

The above code fails with this following exception : Exception Details: System.ArgumentOutOfRangeException: Length cannot be less than zero. Parameter name: length

I request you to tell me which free Mime library I can use to parse Gmail Raw message. Java has a great built-in library called javax.mail.internet (MimeMessage class) which does the job very beautifully. I am using EWS managed Api to work with Exchange online and it's not able to parse Gmail raw message directly.

Edited : removed the encoded message.

best regards,

Solution

As you indicated the string is base64url you have to adapt slightly to overcome the difference from orginal base64 as indicated in the wikipedia article.

The following table shows the differences:

standard  | 62 | 63 | pad
-------------------------
base64    | +  | /  | =
base64Url | -  | _  | N/A

Using this knowledge it becomes clear how to convert from a base64Url to the base64 standard that is used by Convert.FromBase64String.

This code shows how that could work:

var base64Url = "UmVjZWl2 ..... rest of your base64url string ... -";

// replace - and _ with their base64 chars
var sb64 = new StringBuilder(base64Url)
              .Replace('-','+')
              .Replace('_', '/');
var bin = Convert.FromBase64String(sb64.ToString());    

Encoding.ASCII.GetString(bin).Dump("valid");

Using above code dumped the following result in my console (part of it):

Received: from removed.googleusercontent.com
named unknown
by gmailapi.google.com
with HTTPREST;
Sat, 29 Nov 2014 04:55:31 -0800
MIME-Version: 1.0
x-no-auto-attachment: 1
Received: by 10.114.186.6; Mon, 17 Nov 2014 07:11:34 -0800 (PST) Date: Sat, 29 Nov 2014 04:55:31 -0800
Message-Id: [removed for privacy]
Subject: Tips for using your new inbox
From: [removed for privacy]
To: "Your Team @365innovate" <[removed for privacy] >
Content-Type: multipart/alternative; boundary=001a11c33c7aee86ee05080f6437

--001a11c33c7aee86ee05080f6437
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

Tips for using your new inbox
[image: Google]