Send Email with Digital Signature in Managed C++/CLI - S/MIME with SHA1, SHA256 and SHA512¶

#include "stdafx.h"

using namespace System;
using namespace System::Security::Cryptography::X509Certificates;
using namespace EASendMail;

X509Certificate2^ _findCertificate(String ^storeName, String ^emailAddress)
{
    X509Certificate2 ^cert = nullptr;

    X509Store ^store = gcnew X509Store(storeName, StoreLocation::CurrentUser);
    store->Open(OpenFlags::ReadOnly);

    X509Certificate2Collection ^certfiicates = store->Certificates->Find(
        X509FindType::FindBySubjectName, emailAddress, true);

    if (certfiicates->Count > 0)
    {
        cert = certfiicates[0];
    }

    store->Close();
    return cert;
}

int main(array<System::String ^> ^args)
{
    try
    {
        SmtpMail ^oMail = gcnew SmtpMail("TryIt");

        // Set sender email address, please change it to yours
        oMail->From = "test@emailarchitect.net";
        // Set recipient email address, please change it to yours
        oMail->To = gcnew AddressCollection("support@emailarchitect.net");

        // Set email subject
        oMail->Subject = "test email from Managed C++ project with digital signature";
        // Set email body
        oMail->TextBody = "this is a test email sent from Managed C++ project with digital signature";

        X509Certificate2 ^signerCertificate = _findCertificate("My", oMail->From->Address);
        if (signerCertificate == nullptr)
            throw gcnew Exception("No signer certificate found!");

        oMail->From->Certificate2 = signerCertificate;

        // You can also load the signer certificate from a pfx file.
        /* String ^pfxPath = "D:\\TestCerts\\signer.pfx";
        X509Certificate2 ^signerCertFromPfx = gcnew X509Certificate2(pfxPath,
            "nosecret",
            X509KeyStorageFlags::Exportable | X509KeyStorageFlags::UserKeySet);

        oMail->From->Certificate2 = signerCertFromPfx;
        */
        // If you use it in web application,
        // please use  X509KeyStorageFlags::Exportable | X509KeyStorageFlags::MachineKeySet

        // If you use it in .NET core application
        // please use X509KeyStorageFlags::Exportable | X509KeyStorageFlags::EphemeralKeySet

        // Your SMTP server address
        SmtpServer ^oServer = gcnew SmtpServer("smtp.emailarchitect.net");

        // User and password for ESMTP authentication.
        oServer->User = "test@emailarchitect.net";
        oServer->Password = "testpassword";

        // Most mordern SMTP servers require SSL/TLS connection now.
        // ConnectTryTLS means if server supports SSL/TLS, SSL/TLS will be used automatically.
        oServer->ConnectType = SmtpConnectType::ConnectTryTLS;

        // If your SMTP server uses 587 port
        // oServer->Port = 587;

        // If your SMTP server requires SSL/TLS connection on 25/587/465 port
        // oServer->Port = 25; // 25 or 587 or 465
        // oServer->ConnectType = SmtpConnectType::ConnectSSLAuto;

        Console::WriteLine("start to send email with digital signature...");

        SmtpClient ^oSmtp = gcnew SmtpClient();
        oSmtp->SendMail(oServer, oMail);

        Console::WriteLine("email was sent successfully!");
    }
    catch (Exception ^ep)
    {
        Console::WriteLine("failed to send email with the following error:");
        Console::WriteLine(ep->Message);
    }

    return 0;
}