Send Email via C# through Google Apps account

Question

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("someone@somewhere.example");
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 = "emailAddress@mydomain.example";
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?

I'm getting a timeout issue, but looking at all the code smaples, it seems like my code and settings are correct. — Dan Csharpster, Jul 11 '14 at 20:12
Late addition: Google requires you to "Enable less secure apps" for this to work: https://support.google.com/accounts/answer/6010255?hl=en — L_7337, Sep 08 '15 at 13:10

score 95 · Accepted Answer · edited Jun 22 '22 at 09:15

95

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="example@domain.example" deliveryMethod="Network">
          <network host="smtp.gmail.com" port="587"
              userName="example@domain.example" password="password"/>
      </smtp>
    </mailSettings>
  </system.net>
</configuration>

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

var message = new MailMessage("navin@php.net");
// here is an important part:
message.From = new MailAddress("example@domain.example", "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.

edited Jun 22 '22 at 09:15

Stephen Ostermiller

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answered Apr 16 '09 at 20:50

Konstantin Tarkus

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1

the full webconfig is under and should be – Simon_Weaver Oct 10 '09 at 06:10
you can also put the enableSsl in the config. – Shay Erlichmen Mar 06 '10 at 14:13
1

@Shay - how can you enableSSL in the config? – Rinat Abdullin May 23 '10 at 07:36
2

@Rinat its new with .NET 4.0 just put enableSsl in – Shay Erlichmen May 23 '10 at 18:54
Thanks. Added +1. Unfortunately 90% of production application are still .NET 3.5 and below. Esp. ones on the Azure. – Rinat Abdullin May 24 '10 at 13:08
Why this port number is not listed in the google instructions I do not know! – Stokedout Dec 13 '12 at 03:10
You can enable SSL by adding enableSsl in the network element in the web.config: – Pedro Jan 22 '15 at 05:13

score 9 · Answer 2 · edited Jul 08 '20 at 19:50

This is what I use in WPF 4

SmtpClient client = new SmtpClient();
client.Credentials = new NetworkCredential("sender_email@domain.tld", "P@$$w0rD");
client.Port = 587;
client.Host = "smtp.gmail.com";
client.EnableSsl = true;

try 
{
    MailAddress maFrom = new MailAddress("sender_email@domain.tld", "Sender's Name", Encoding.UTF8),
    MailAddress maTo = new MailAddress("recipient_email@domain2.tld", "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...

I want to make a "contact us" page so users send emails to site-admin. Is there a way to set "From" to their email address?? — Shimmy Weitzhandler, Dec 22 '12 at 22:59
You can spoof the sender's address; but there's a good risk of getting your email marked as spam. I suggest you send an email from info@yourhost.tld to both admin and the person who's trying to contact you. Then your admin can send a reply to all. — Achilles, Dec 23 '12 at 03:48
There's a small bug here, causing the display names to be thrown away. The MailMessage construction should look like this: MailMessage mmsg = new MailMessage(maFrom, maTo); — Kevin Meboe, Jul 08 '20 at 16:50

score 4 · Answer 3 · answered Dec 12 '09 at 17:04

4

change the port to 465

answered Dec 12 '09 at 17:04

sf.

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score 3 · Answer 4 · edited Feb 20 '12 at 07:47

3

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.

edited Feb 20 '12 at 07:47

Peter O.

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answered Feb 20 '12 at 07:33

Jeevan

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Given that the OP's code seems fine, this may actually have been the problem. – Dermot Jul 11 '12 at 00:26

score 0 · Answer 5 · answered Dec 16 '17 at 15:54

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

Send Email via C# through Google Apps account

5 Answers5

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