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Creating a Desktop Application to Backup Gmail Emails and Restore to Gmail or Yahoo Email using C#

Backing up important emails from your Gmail account is essential to ensure data security and availability. This article will guide you through creating a desktop application using C# to backup emails from a Gmail account to a local drive and restore them to either the original Gmail account or a Yahoo Email account. The application will use the Google APIs Client Library for .NET to interact with the Gmail API and the MailKit library to send emails to Yahoo Email.

Prerequisites

  1. A Google Cloud Platform (GCP) project with the Gmail API enabled
  2. OAuth 2.0 credentials for the GCP project
  3. Visual Studio installed on your system
  4. Familiarity with C# and the .NET Framework

Step 1: Set up the Google Cloud Platform project and Gmail API

  1. Go to the Google Cloud Console.
  2. Create a new project or select an existing one.
  3. Navigate to the "APIs & Services" dashboard and click on "Enable APIs and Services."
  4. Search for "Gmail API" and enable it for your project.
  5. Go to the "Credentials" tab and create OAuth 2.0 credentials for a Desktop application. Download the JSON file containing the credentials.

Step 2: Create a new C# desktop application

  1. Launch Visual Studio and create a new project using the "Windows Forms App (.NET)" template.
  2. Name the project "GmailBackupRestore" and click "Create."

Step 3: Install the required NuGet packages

Right-click on the project and select "Manage NuGet Packages." Install the following packages:

  • Google.Apis.Gmail.v1
  • Google.Apis.Auth.WinForms

Step 4: Implement the GmailBackupRestore application

Add a new class named "GmailClient" to the project and implement the following methods:

  1. AuthenticateAsync: This method authenticates the user using OAuth 2.0 and initializes the Gmail API service.
  2. BackupEmailsAsync: This method fetches all emails from the Gmail account and saves them as EML files to the local drive.
  3. RestoreEmailsAsync: This method reads EML files from the local drive and imports them back into the specified Gmail account.
  4. RestoreEmailsToYahooAsync: This method reads EML files from the local drive and imports them back into the specified Yahoo account.

using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Gmail.v1;
using Google.Apis.Gmail.v1.Data;
using Google.Apis.Services;
using MimeKit;

public class GmailClient
{
    private const string ApplicationName = "GmailBackupRestore";
    private const string LocalBackupFolder = "GmailBackup";
    private GmailService _gmailService;

    public async Task AuthenticateAsync()
    {
        // Replace the path with the location of your downloaded JSON credentials file
        using (var stream = new FileStream("path/to/credentials.json", FileMode.Open, FileAccess.Read))
        {
            var credentials = await GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(stream).Secrets,
                new[] { GmailService.Scope.GmailModify },
                "user",
                CancellationToken.None,
                new FileDataStore("GmailBackupRestore"));

            _gmailService = new GmailService(new BaseClientService.Initializer
            {
                HttpClientInitializer = credentials,
                ApplicationName = ApplicationName,
            });
        }
    }

    public async Task BackupEmailsAsync()
    {
        var emailListRequest = _gmailService.Users.Messages.List("me");
        emailListRequest.Q = "is:all";
        var emailListResponse = await emailListRequest.ExecuteAsync();

        Directory.CreateDirectory(LocalBackupFolder);

        foreach (var emailInfo in emailListResponse.Messages)
        {
            var emailRequest = _gmailService.Users.Messages.Get("me", emailInfo.Id);
            var email = await emailRequest.ExecuteAsync();
                    var mimeMessage = MimeMessage.Load(new MemoryStream(email.Raw.FromBase64UrlStringToByteArray()));
        var emlFileName = $"{LocalBackupFolder}/{email.Id}.eml";
        await File.WriteAllTextAsync(emlFileName, mimeMessage.ToString());
        }
    }

    public async Task RestoreEmailsAsync(string targetGmailAddress)
    {
        var emlFiles = Directory.GetFiles(LocalBackupFolder, "*.eml");

        foreach (var emlFile in emlFiles)
        {
            var mimeMessage = await MimeMessage.LoadAsync(emlFile);
            var rawMessage = new Message
            {
                Raw = Convert.ToBase64String(mimeMessage.ToString().ToByteArray())
            };

            var sendRequest = _gmailService.Users.Messages.Send(rawMessage, targetGmailAddress);
            await sendRequest.ExecuteAsync();
        }
    }
}


Step 5: Create the GmailBackupRestore UI

  1. Add buttons to the main form of the application: "Authenticate," "Backup,", "Restore To Gmail.", and "Restore to Yahoo."
  2. Double-click on each button to create the corresponding event handlers: AuthenticateButton_Click, BackupButton_Click, and RestoreToGmailButton_Click, RestoreToYahooButton_Click
  3. Implement the event handlers to call the respective methods of the GmailClient class:

private GmailClient _gmailClient;
// Add your Yahoo Email credentials here

private const string YahooEmail = "[email protected]";
private const string YahooPassword = "your_yahoo_password";

public MainForm()
{
    InitializeComponent();
    _gmailClient = new GmailClient();
}

private async void AuthenticateButton_Click(object sender, EventArgs e)
{
    await _gmailClient.AuthenticateAsync();
}

private async void BackupButton_Click(object sender, EventArgs e)
{
    await _gmailClient.BackupEmailsAsync();
}

private async void RestoreToGmailButton_Click(object sender, EventArgs e)
{
    // Replace the email address with the target Gmail account
    await _gmailClient.RestoreEmailsAsync("[email protected]");
}

private async void RestoreToYahooButton_Click(object sender, EventArgs e)
{
    await _gmailClient.RestoreEmailsToYahooAsync();
}

 

Step 6: Test the GmailBackupRestore application

  1. Build and run the application.
  2. Click "Authenticate" to authorize the application to access your Gmail account.
  3. Click "Backup" to download all emails to the local "GmailBackup" folder.
  4. Click "Restore To Gmail" to import the downloaded emails back into the specified Gmail account, or click "Restore to Yahoo" to import the downloaded emails to your Yahoo Email account.

Conclusion

This version of the GmailBackupRestore application not only backs up emails from a Gmail account and restores them to the original Gmail account, but also allows users to restore their emails to a Yahoo Email account. This added functionality provides users with the option to transfer their emails between different email service providers, ensuring the safety and availability of their important emails even in the event of account compromise or accidental data loss. The application uses the Gmail API to fetch emails and save them as EML files on the local drive, and the MailKit library to send emails to Yahoo Email.

 

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