Visual C++ - Send email using Gmail SMTP server

The following c++ example codes demonstrate how to send email using Gmail SMTP server.

Gmail SMTP Server

Gmail SMTP server address is smtp.gmail.com. It requires implicit SSL or explicit SSL (TLS) connection, and you should use your Gmail email address as the user name for ESMTP authentication.

Server Port SSL/TLS
smtp.gmail.com 25, 587 TLS
smtp.gmail.com 465 SSL

Gmail App Password

To help keep your account secure, starting May 30, 2022, ​​Google will no longer support the use of third-party apps or devices which ask you to sign in to your Google Account using only your username and password.

Therefore, you should sign in using App Passwords. An App Password is a 16-digit passcode that gives a less secure app or device permission to access your Google Account. App Passwords can only be used with accounts that have 2-Step Verification turned on. You need to use App Password instead of the user password for user authentication.

Another solution is Gmail OAUH, please see Gmail SMTP OAUTH section.

Installation

EASendMail is a SMTP component which supports all operations of SMTP/ESMTP protocols (RFC 821, RFC 822, RFC 2554). Before you can use the following example codes, you should download the EASendMail Installer and install it on your machine at first.

Add reference

To use EASendMail SMTP ActiveX Object in your C++ project, the first step is “Add header files of EASendMail to your project”. Please go to C:\Program Files\EASendMail\Include\tlh or C:\Program Files (x86)\EASendMail\Include\tlh folder, find easendmailobj.tlh and easendmailobj.tli, and then copy these files to your project folder.

add reference in Visual C++

C++ - Send email using Gmail SMTP server - example

The following example codes demonstrate sending email using Gmail SMTP server. In order to run it correctly, please change SMTP server, user, password, sender, recipient value to yours.

Note

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

#include "stdafx.h"
#include <tchar.h>
#include <Windows.h>

#include "EASendMailObj.tlh"
using namespace EASendMailObjLib;

const int ConnectNormal = 0;
const int ConnectSSLAuto = 1;
const int ConnectSTARTTLS = 2;
const int ConnectDirectSSL = 3;
const int ConnectTryTLS = 4;

int _tmain(int argc, _TCHAR* argv[])
{
    ::CoInitialize(NULL);

    IMailPtr oSmtp = NULL;
    oSmtp.CreateInstance(__uuidof(EASendMailObjLib::Mail));
    oSmtp->LicenseCode = _T("TryIt");

    // Set your gmail email address
    oSmtp->FromAddr = _T("gmailid@gmail.com");

    // Add recipient email address
    oSmtp->AddRecipientEx(_T("support@emailarchitect.net"), 0);

    // Set email subject
    oSmtp->Subject = _T("simple email from Visual C++ with gmail account");

    // Set email body
    oSmtp->BodyText = _T("this is a test email sent from Visual C++ project with Gmail");

    // Gmail SMTP server address
    oSmtp->ServerAddr = _T("smtp.gmail.com");

    // Gmail user authentication should use your
    // Gmail email address as the user name.
    // For example: your email is "gmailid@gmail.com", then the user should be "gmailid@gmail.com"
    oSmtp->UserName = _T("gmailid@gmail.com");

    // Create app password in Google account
    // https://support.google.com/accounts/answer/185833?hl=en
    oSmtp->Password = _T("your app password");

    // If you want to use direct SSL 465 port,
    // Please add this line, otherwise TLS will be used.
    // oSmtp->ServerPort = 465;

    // Set 25 or 587 SMTP port
    oSmtp->ServerPort = 587;

    // detect SSL/TLS automatically
    oSmtp->ConnectType = ConnectSSLAuto;

    _tprintf(_T("Start to send email via gmail account ...\r\n"));

    if(oSmtp->SendMail() == 0)
    {
        _tprintf(_T("email was sent successfully!\r\n"));
    }
    else
    {
        _tprintf(_T("failed to send email with the following error: %s\r\n"),
            (const TCHAR*)oSmtp->GetLastErrDescription());
    }

    return 0;
}

Gmail SMTP 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.

TLS 1.2 protocol

TLS is the successor of SSL, more and more SMTP servers require TLS 1.2 encryption now.

If your operating system is Windows XP/Vista/Windows 7/Windows 2003/2008/2008 R2/2012/2012 R2, you need to enable TLS 1.2 protocol in your operating system like this:

Enable TLS 1.2 on Windows XP/Vista/7/10/Windows 2008/2008 R2/2012

32bit/x64 ActiveX DLL

Seperate builds of run-time dll for 32 and x64 platform

File Platform
Installation Path\Lib\native\x86\EASendMailObj.dll 32 bit
Installation Path\Lib\native\x64\EASendMailObj.dll 64 bit

Distribution

  • Standard EXE

    For VB6, C++, Delphi or other standard exe application, you can distribute EASendMailObj.dll with your application to target machine without COM-registration and installer. To learn more detail, please have a look at Registration-free COM with Manifest File.

  • Script

    For ASP, VBScript, VBA, MS SQL Stored Procedure, you need to install EASendMail on target machine by EASendMail installer, both 32bit/x64 DLL are installed and registered.

Appendix

Comments

If you have any comments or questions about above example codes, please click here to add your comments.