Managed C++/CLI - Retrieve Email from Gmail Account

The following C++/CLI example codes demonstrate how to retrieve email from Gmail IMAP4 server.

Gmail POP3 and IMAP4 Setting

Gmail POP3 server address is pop.gmail.com. It requires SSL connection on 995 port, and you should use your Gmail email address as the user name for user authentication.

Gmail IMAP4 server address is imap.gmail.com. It requires SSL connection on 993 port, and you should use your Gmail email address as the user name for user authentication. For example: your email is gmailid@gmail.com, and then the user name should be gmailid@gmail.com.

To retrieve email from Gmail account, you need to enable POP3 or IMAP4 access in your gmail account settings.

Because Gmail POP3 server doesn’t work like normal POP3 server, it hides old emails automatically even the email was not deleted, so we suggest that you use IMAP4 protocol.

Server Port SSL Protocol
pop.gmail.com 995 SSL required Pop3
imap.gmail.com 993 SSL required Imap4 (recommended)

Important

If you got authentication error, you need to enable Allowing less secure apps or Sign in using App Passwords.

Another way is Gmail OAUH, please see Gmail IMAP OAUTH section.

Installation

Before you can use the following sample codes, you should download the EAGetMail Installer and install it on your machine at first. Full sample projects are included in this installer.

Install from NuGet

You can also install the run-time assembly by NuGet. Run the following command in the NuGet Package Manager Console:

Install-Package EAGetMail

Note

If you install it by NuGet, no sample projects are installed, only .NET assembly is installed.

Add Reference

To use EAGetMail POP3 & IMAP Component in your project, the first step is “Add reference of EAGetMail to your project”. Please create or open your project with Visual Studio, then go to menu -> Project -> Add Reference -> .NET -> Browse..., and select Installation path\Lib\[netversion]\EAGetMail.dll, click Open-> OK, the reference will be added to the project, you can start to use it to retrieve email and parse email in your project.

add reference in c#/vb.net/managed c++/cli

.NET Assembly

Because EAGetMail has separate builds for .Net Framework, please refer to the following table and choose the correct dll.

Separate builds of run-time assembly for .Net Framework 1.1, 2.0, 3.5, 4.0, 4.5, 4.61, .NET Core 2.1 and .Net Compact Framework 2.0, 3.5.

File .NET Framework Version
Lib\net11\EAGetMail.dll Built with .NET Framework 1.1
It requires .NET Framework 1.1, 2.0, 3.5 or later version.
Lib\net20\EAGetMail.dll Built with .NET Framework 2.0
It requires .NET Framework 2.0, 3.5 or later version.
Lib\net35\EAGetMail.dll Built with .NET Framework 3.5
It requires .NET Framework 3.5 or later version.
Lib\net40\EAGetMail.dll Built with .NET Framework 4.0
It requires .NET Framework 4.0 or later version.
Lib\net45\EAGetMail.dll Built with .NET Framework 4.5
It requires .NET Framework 4.5 or later version.
Lib\net461\EAGetMail.dll Built with .NET Framework 4.6.1
It requires .NET Framework 4.6.1 or later version.
Lib\netcoreapp2.1\EAGetMail.dll Built with .NET Core 2.1
It requires .NET Core 2.1 or later version.
Lib\net20-cf\EAGetMail.dll Built with .NET Compact Framework 2.0
It requires .NET Compact Framework 2.0, 3.5 or later version.
Lib\net35-cf\EAGetMail.dll Built with .NET Compact Framework 3.5
It requires .NET Compact Framework 3.5 or later version.

Managed C++/CLI - Retrieve Email from Gmail Account - Example

The following example codes demonstrate how to use EAGetMail POP3 component to download email from Gmail IMAP server. In order to run it correctly, please change email server, user, password, folder, file name value to yours.

Note

To get full sample projects, please download and install EAGetMail on your machine.

Because Gmail POP3 server doesn’t work like normal POP3 server, it hides old emails automatically even the email was not deleted, so we suggest that you use IMAP4 protocol.

#include "stdafx.h"

using namespace System;
using namespace System::Globalization;
using namespace System::IO;
using namespace EAGetMail; //add EAGetMail namespace

// Generate an unqiue email file name based on date time
static String ^ _generateFileName(int sequence)
{
    DateTime currentDateTime = DateTime::Now;
    return String::Format("{0}-{1:000}-{2:000}.eml",
        currentDateTime.ToString("yyyyMMddHHmmss", gcnew CultureInfo("en-US")),
        currentDateTime.Millisecond,
        sequence);
}

int main(array<System::String ^> ^args)
{
    try
    {
        // Create a folder named "inbox" under current directory
        // to save the email retrieved.
        String ^localInbox = String::Format("{0}\\inbox", Directory::GetCurrentDirectory());

        // If the folder is not existed, create it.
        if (!Directory::Exists(localInbox))
        {
            Directory::CreateDirectory(localInbox);
        }

        // Gmail IMAP server is "imap.gmail.com"
        MailServer ^oServer = gcnew MailServer("imap.gmail.com",
            "gmailid@gmail.com",
            "yourpassword",
            ServerProtocol::Imap4);

        // Enable SSL connection
        oServer->SSLConnection = true;
        // Set 993 IMAP4 SSL port
        oServer->Port = 993;

        Console::WriteLine("Connecting server ...");

        MailClient ^oClient = gcnew MailClient("TryIt");
        oClient->Connect(oServer);

        array<MailInfo^> ^infos = oClient->GetMailInfos();
        Console::WriteLine("Total {0} email(s)\r\n", infos->Length);

        for (int i = 0; i < infos->Length; i++)
        {
            MailInfo ^info = infos[i];
            Console::WriteLine("Index: {0}; Size: {1}; UIDL: {2}",
                info->Index, info->Size, info->UIDL);

            // Generate an unqiue email file name based on date time
            String^ fileName = _generateFileName(i + 1);
            String^ fullPath = String::Format("{0}\\{1}", localInbox, fileName);

            // Receive email from IMAP server
            Mail ^oMail = oClient->GetMail(info);
            Console::WriteLine("From: {0}", oMail->From->ToString());
            Console::WriteLine("Subject: {0}\r\n", oMail->Subject);

            // Save email to local disk
            oMail->SaveAs(fullPath, true);

            // Mark email as deleted from IMAP server.
            oClient->Delete(info);
        }

        // Quit and expunge emails marked as deleted from IMAP server.
        oClient->Quit();
        Console::WriteLine("Completed!");
    }
    catch (Exception ^ep)
    {
        Console::WriteLine(ep->Message);
    }

    return 0;
}

Gmail IMAP OAUTH

The Gmail IMAP and SMTP servers have been extended to support authorization via the industry-standard OAuth 2.0 protocol. Using OAUTH protocol, user can do authentication by Gmail Web OAuth instead of inputting user and password directly in application. This way is more secure, but a little bit complex.

Using Gmail IMAP OAUTH

Managed C++/CLI - Retrieve Unread/New Email from Gmail Account - Example

Because IMAP/EWS/WebDAV support read mail flag, with this feature, we can also retrieve unread/new email only from Gmail like this

#include "stdafx.h"

using namespace System;
using namespace System::Globalization;
using namespace System::IO;
using namespace EAGetMail; //add EAGetMail namespace

// Generate an unqiue email file name based on date time
static String ^ _generateFileName(int sequence)
{
    DateTime currentDateTime = DateTime::Now;
    return String::Format("{0}-{1:000}-{2:000}.eml",
        currentDateTime.ToString("yyyyMMddHHmmss", gcnew CultureInfo("en-US")),
        currentDateTime.Millisecond,
        sequence);
}

int main(array<System::String ^> ^args)
{
    try
    {
        // Create a folder named "inbox" under current directory
        // to save the email retrieved.
        String ^localInbox = String::Format("{0}\\inbox", Directory::GetCurrentDirectory());

        // If the folder is not existed, create it.
        if (!Directory::Exists(localInbox))
        {
            Directory::CreateDirectory(localInbox);
        }

        // Gmail IMAP server is "imap.gmail.com"
        MailServer ^oServer = gcnew MailServer("imap.gmail.com",
            "gmailid@gmail.com",
            "yourpassword",
            ServerProtocol::Imap4);

        // Enable SSL connection
        oServer->SSLConnection = true;
        // Set 993 IMAP4 SSL port
        oServer->Port = 993;

        Console::WriteLine("Connecting server ...");

        MailClient ^oClient = gcnew MailClient("TryIt");
        oClient->Connect(oServer);

        // retrieve unread/new email only
        oClient->GetMailInfosParam->Reset();
        oClient->GetMailInfosParam->GetMailInfosOptions = GetMailInfosOptionType::NewOnly;

        array<MailInfo^> ^infos = oClient->GetMailInfos();
        Console::WriteLine("Total {0} unread email(s)\r\n", infos->Length);

        for (int i = 0; i < infos->Length; i++)
        {
            MailInfo ^info = infos[i];
            Console::WriteLine("Index: {0}; Size: {1}; UIDL: {2}",
                info->Index, info->Size, info->UIDL);

            // Generate an unqiue email file name based on date time
            String^ fileName = _generateFileName(i + 1);
            String^ fullPath = String::Format("{0}\\{1}", localInbox, fileName);

            // Receive email from IMAP server
            Mail ^oMail = oClient->GetMail(info);
            Console::WriteLine("From: {0}", oMail->From->ToString());
            Console::WriteLine("Subject: {0}\r\n", oMail->Subject);

            // Save email to local disk
            oMail->SaveAs(fullPath, true);

            // mark unread email as read, next time this email won't be retrieved again
            if (!info->Read)
            {
                oClient->MarkAsRead(info, true);
            }

            // if you don't want to leave a copy on server, please use
            // oClient->Delete(info);
            // instead of MarkAsRead
        }

        // Quit and expunge emails marked as deleted from IMAP server.
        oClient->Quit();
        Console::WriteLine("Completed!");
    }
    catch (Exception ^ep)
    {
        Console::WriteLine(ep->Message);
    }

    return 0;
}

Appendix

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