How to use SMTP in ASP.NET Core

I'm developing an ASP.NET Core project and get an error when using SMTP.

This is my current code:

string code = GenerateRandom6DigitString();
string subject = "Your Verification Code";

string body = $"Welcome to website!!!\n\nYour verification code is: **{code}**.\n\nPlease enter this code to verify your account.\n\nThank you!";

string myEmail = Environment.GetEnvironmentVariable("EMAIL_ADDRESS") ?? string.Empty;
string myEmailPassword = Environment.GetEnvironmentVariable("EMAIL_PASSWORD") ?? string.Empty;
string mySmtpHost = Environment.GetEnvironmentVariable("SMTP_HOST") ?? string.Empty;

MailMessage mail = new MailMessage();
mail.From = new MailAddress(myEmail);
mail.To.Add(email);
mail.Subject = subject;
mail.Body = body;
mail.IsBodyHtml = false;

SmtpClient smtpClient = new SmtpClient(mySmtpHost, 587)
        {
            Credentials = new NetworkCredential(myEmail, myEmailPassword),
            EnableSsl = true,
            UseDefaultCredentials = false,
            DeliveryMethod = SmtpDeliveryMethod.Network,
        };

try
{
    smtpClient.Send(mail);

    lock (lockVerifyValueDict)
    {
        verifyValueDict.Add(email, code);
    }

    return true;
}
catch (Exception ex)
{
    Console.WriteLine($"Failed to send email. Email: {email} Error: {ex.Message}");
    return false;
}

And env file is as following:

EMAIL_ADDRESS=myname@gmail.com
EMAIL_PASSWORD=password
SMTP_HOST=smtp.gmail.com

But I can't send any mail using this code.

In my opinion, it's because of google security settings.

If anybody know about google security settings for smtp, please help me.

Thank you.

You doesn't have to enable anything specific in GMail. In case you're using 2FA you must create an app password which you can do here. I tested it on my own account with MailKit using the following code:

using MimeMessage message = new();
message.From.Add(InternetAddress.Parse("myAddress@gmail.com"));
message.To.Add(InternetAddress.Parse("targetAddress@gmail.com"));
message.Subject = "Message send from C#";

using SmtpClient client = new();
await client.ConnectAsync("smtp.gmail.com", 587);
await client.AuthenticateAsync("myAddress@gmail.com", "The pwd or app pwd");
await client.SendAsync(message);