Gmail 草稿(带附件的 HTML)与 MimeKit、C# Winforms 和 Google API

做你想做的最简单的方法是这样的：

static string Base64UrlEncode (MimeMessage message)
{
    using (var stream = new MemoryStream ()) {
        message.WriteTo (stream);
        return Convert.ToBase64String (stream.GetBuffer (), 0, (int) stream.Length)
            .Replace ('+', '-')
            .Replace ('/', '_')
            .Replace ("=", "");
    }
}

但更有效的方法需要实现我们自己的 UrlEncoderFilter 来替换您的".替换 （...）" 逻辑：

using MimeKit;
using MimeKit.IO;
using MimeKit.IO.Filters;
// ...
class UrlEncodeFilter : IMimeFilter
{
    byte[] output = new byte[8192];
    #region IMimeFilter implementation
    public byte[] Filter (byte[] input, int startIndex, int length, out int outputIndex, out int outputLength)
    {
        if (output.Length < input.Length)
            Array.Resize (ref output, input.Length);
        int endIndex = startIndex + length;
        outputLength = 0;
        outputIndex = 0;
        for (int index = startIndex; index < endIndex; index++) {
            switch ((char) input[index]) {
            case ''r': case ''n': case '=': break;
            case '+': output[outputLength++] = (byte) '-'; break;
            case '/': output[outputLength++] = (byte) '_'; break;
            default: output[outputLength++] = input[index]; break;
            }
        }
        return output;
    }
    public byte[] Flush (byte[] input, int startIndex, int length, out int outputIndex, out int outputLength)
    {
        return Filter (input, startIndex, length, out outputIndex, out outputLength);
    }
    public void Reset ()
    {
    }
    #endregion
}

你使用它的方式是这样的：

static string Base64UrlEncode (MimeMessage message)
{
    using (var stream = new MemoryStream ()) {
        using (var filtered = new FilteredStream (stream)) {
            filtered.Add (EncoderFilter.Create (ContentEncoding.Base64));
            filtered.Add (new UrlEncodeFilter ());
            message.WriteTo (filtered);
            filtered.Flush ();
        }
        return Encoding.ASCII.GetString (stream.GetBuffer (), 0, (int) stream.Length);
    }
}

这是我用来创建带有附件的 gmail 草稿的 C# 代码......

using System;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Gmail.v1;
using Google.Apis.Services;
using Google.Apis.Util.Store;
using System.IO;
using System.Threading;
using System.Net.Mail;
namespace SendStatusReportsAddin1
{
    class Program
    {
        // If modifying these scopes, delete your previously saved credentials
        // at ~/.credentials/gmail-dotnet-quickstart.json
        //static string[] Scopes = { GmailService.Scope.GmailReadonly };
        static string[] Scopes = { GmailService.Scope.MailGoogleCom };
        static string ApplicationName = "Gmail API .NET Quickstart";
        static void Main(string[] args)
        {
            //Authorization
              UserCredential credential;
              using (var stream =
                  new FileStream("client_secret2.json", FileMode.Open, FileAccess.Read))
              {
                  string credPath = System.Environment.GetFolderPath(
                      System.Environment.SpecialFolder.Personal);
                  credPath = Path.Combine(credPath, ".credentials3/gmail-dotnet.json");
                  credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                      GoogleClientSecrets.Load(stream).Secrets,
                      Scopes,
                      "user",
                      CancellationToken.None,
                      new FileDataStore(credPath, true)).Result;
                  Console.WriteLine("Credential file saved to: " + credPath);
              }
            //Create Gmail API service.
              var service = new GmailService(new BaseClientService.Initializer()
              {
                  HttpClientInitializer = credential,
                  ApplicationName = ApplicationName,
              });
            //Create mail message
              MailMessage mailmsg = new MailMessage();
              {
                  mailmsg.Subject = "My test subject";
                  mailmsg.Body = "<b>My smart message </b>";
                  mailmsg.From = new MailAddress("joe.blow@hotmail.com");
                  mailmsg.To.Add(new MailAddress("jeff.jones@gmail.com"));
                  mailmsg.IsBodyHtml = true;
              }
            //add attachment
              string statusreportfile =
                        @"C:'Users'ey96a'Google Drive'10 Status-Vacation-Expense'Status Reports'UUM RewriteStatus Report.pdf";
              Attachment data = new Attachment(statusreportfile);
              mailmsg.Attachments.Add(data);
            //Make mail message a Mime message
              MimeKit.MimeMessage mimemessage = MimeKit.MimeMessage.CreateFromMailMessage(mailmsg);
            //Use Base64URLEncode to encode the Mime message
              Google.Apis.Gmail.v1.Data.Message finalmessage = new Google.Apis.Gmail.v1.Data.Message();
              finalmessage.Raw = Base64UrlEncode(mimemessage.ToString());
            //Create the draft email
              var mydraft = new Google.Apis.Gmail.v1.Data.Draft();
              mydraft.Message = finalmessage;
              var resultdraft = service.Users.Drafts.Create(mydraft, "me").Execute();
            //Send the email (instead of creating a draft)
              var resultsend = service.Users.Messages.Send(finalmessage, "me").Execute();
            //Open the SendStatusReports form
              aOpenForm.myForm1();
        }  //end of Main
        //Base64 URL encode
        public static string Base64UrlEncode(string input)
        {
            var inputBytes = System.Text.Encoding.UTF8.GetBytes(input);
            // Special "url-safe" base64 encode.
            return System.Convert.ToBase64String(inputBytes)
                .Replace('+', '-')
                .Replace('/', '_')
                .Replace("=", "");
        }
    } //end of class Program
}

如果做不到这一点，有没有办法创建一个AE。在编码之前采用HTML格式的Net.Mail消息？

你可以试试

msg.ContentType = "text/html"; 

在您的 AE 中。网络邮件邮件消息