Send Email via C# through Google Apps account

C# Problem Overview

I have a standard Google Apps account. I have setup a custom domain through Google Apps. I am able to send and receive emails successfully through Google Apps when I use the Gmail interface. However, I want to send an email via code. In order to attempt this, I have been trying the following code:

MailMessage mailMessage = new MailMessage();
mailMessage.To.Add("[email protected]");
mailMessage.Subject = "Test";
mailMessage.Body = "<html><body>This is a test</body></html>";
mailMessage.IsBodyHtml = true;

// Create the credentials to login to the gmail account associated with my custom domain
string sendEmailsFrom = "[email protected]";             
string sendEmailsFromPassword = "password";
NetworkCredential cred = new NetworkCredential(sendEmailsFrom, sendEmailsFromPassword);

SmtpClient mailClient = new SmtpClient("smtp.gmail.com", 587);
mailClient.EnableSsl = true;
mailClient.DeliveryMethod = SmtpDeliveryMethod.Network;
mailClient.UseDefaultCredentials = false;
mailClient.Timeout = 20000;
mailClient.Credentials = cred;
mailClient.Send(mailMessage);

When the Send method is reached, an Exception is thrown that states:

> "The SMTP server requires a secure > connection or the client was not > authenticated. The server response > was: 5.5.1 Authentication Required."

How do I send emails through my custom domain via Google?

Thanks!

C# Solutions

Solution 1 - C#

There is no need to hardcode all smtp settings in your code. Put them in web.config instead. This way you can encrypt these settings if needed and change them on the fly without recompiling your application.

<configuration>
  <system.net>
    <mailSettings>
      <smtp from="[email protected]" deliveryMethod="Network">
          <network host="smtp.gmail.com" port="587"
              userName="[email protected]" password="password"/>
      </smtp>
    </mailSettings>
  </system.net>
</configuration>

End when you send email just enable SSL on your SmtpClient:

var message = new MailMessage("[email protected]");
// here is an important part:
message.From = new MailAddress("[email protected]", "Mailer");
// it's superfluous part here since from address is defined in .config file
// in my example. But since you don't use .config file, you will need it.

var client = new SmtpClient();
client.EnableSsl = true;
client.Send(message);

Make sure that you're sending email from the same email address with which you're trying to authenticate at Gmail.

Note: Starting with .NET 4.0 you can insert enableSsl="true" into web.config as opposed to setting it in code.

Solution 2 - C#

This is what I use in WPF 4

SmtpClient client = new SmtpClient();
client.Credentials = new NetworkCredential("[email protected]", "P@$$w0rD");
client.Port = 587;
client.Host = "smtp.gmail.com";
client.EnableSsl = true;

try 
{
	MailAddress maFrom = new MailAddress("[email protected]", "Sender's Name", Encoding.UTF8),
	MailAddress maTo = new MailAddress("[email protected]", "Recipient's Name", Encoding.UTF8);
	MailMessage mmsg = new MailMessage(maFrom, maTo);
	mmsg.Body = "<html><body><h1>Some HTML Text for Test as BODY</h1></body></html>";
	mmsg.BodyEncoding = Encoding.UTF8;
	mmsg.IsBodyHtml = true;
	mmsg.Subject = "Some Other Text as Subject";
	mmsg.SubjectEncoding = Encoding.UTF8;

	client.Send(mmsg);
	MessageBox.Show("Done");
} 
catch (Exception ex) 
{
	MessageBox.Show(ex.ToString(), ex.Message);
	//throw;
}

Watch for Firewalls and Anti-Viruses. These creepy things tend to block applications sending email. I use McAfee Enterprise and I have to add the executable name (like Bazar.* for both Bazar.exe and Bazar.vshost.exe) to be able to send emails...

Solution 3 - C#

change the port to 465

Solution 4 - C#

There is not need to do anything. Just login in your current account first time and follow instructions.

Your problem will resolve. It occur because you had created the account in google apps but did not login. Just login and follow the instructions and try.

Solution 5 - C#

My code is connecting to smtp.google.com using TLS on Port=587 (SSL should be port 465) but still needs EnableSsl=true

SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com";
smtp.Port = 587;
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
NetworkCredential credentials = new NetworkCredential();
credentials.UserName = "INSERT EMAIL";
credentials.Password = "INSERT PASSWORD";
smtp.Credentials = credentials;

MailAddress addressFrom = new MailAddress(credentials.UserName);
MailAddress addressTo = new MailAddress("INSERT RECIPIENT");
MailMessage msg = new MailMessage(addressFrom, addressTo);
msg.Subject = "SUBJECT"
msg.Body = "BODY";

smtp.Send(msg);

Notice these important prerequisites on your G SUITE account

Ensure that the username you use has cleared the CAPTCHA word verification test that appears when you first sign in.
Ensure that the account has a secure password - https://support.google.com/accounts/answer/32040
Make sure that Less secure apps is enabled for the desired account- https://support.google.com/a/answer/6260879

Content Type	Original Author	Original Content on Stackoverflow
Question	user70192	View Question on Stackoverflow
Solution 1 - C#	Konstantin Tarkus	View Answer on Stackoverflow
Solution 2 - C#	Achilles	View Answer on Stackoverflow
Solution 3 - C#	sf.	View Answer on Stackoverflow
Solution 4 - C#	Jeevan	View Answer on Stackoverflow
Solution 5 - C#	Christian Ernst Rysgaard	View Answer on Stackoverflow