Trouble using C# SmtpClient with Gmail

Other Questions Gmail
1

I’m working on a school project to create an email client. I’ve got it working with most servers using SmtpClient in C#, but Gmail is giving me headaches. I think it’s because of TLS, but setting EnableSsl = true didn’t fix it.

Here’s a simplified version of my code:

var client = new SmtpClient("smtp.gmail.com", 587)
{
    EnableSsl = true,
    UseDefaultCredentials = false,
    Credentials = new NetworkCredential("[email protected]", "mypassword")
};

var message = new MailMessage
{
    To = { "[email protected]" },
    From = new MailAddress("[email protected]"),
    Subject = "Hello",
    Body = "This is a test email"
};

try
{
    client.Send(message);
    Console.WriteLine("Email sent successfully");
}
catch (Exception ex)
{
    Console.WriteLine($"Failed to send email: {ex.Message}");
}

When I run this, I get an error about SSL authentication failing. Any ideas what I’m doing wrong or how to fix this? I’m stumped!

2

hey ryan, i had the same issue. turns out gmail blocked my app cuz of security stuff. try using an app password instead of ur regular one. go to ur google account settings, turn on 2-step verification, then make an app password. use that in ur code. also make sure ur using the latest .NET version. hope this helps!

3

I had a similar experience with Gmail and C# SmtpClient in an earlier project. The issue stemmed from Google’s tightened security measures against less secure apps. One approach that worked for me was to enable 2-Step Verification on the Google account and then generate an app-specific password for the application. Be sure to replace your regular password with this new one when initializing your NetworkCredential. In addition, verify that you are using the latest .NET version since earlier releases might not fully support TLS 1.2. If you still encounter problems, using a library like MailKit proved to be an effective alternative.

4

In my experience with Gmail SMTP issues in C#, the underlying problem is often due to Google’s enhanced security settings. You might resolve this by enabling 2-Step Verification on your Google account and then using an app-specific password for your application instead of your regular one. It is also important to ensure that your application targets .NET Framework 4.5 or later to support the necessary TLS protocols. If problems continue, consider third-party libraries such as MailKit, which handle many of these complexities automatically. Additionally, checking your account settings regarding access for less secure apps might be helpful, although it is not recommended for long-term use.