Send Mail is not working asp.net web forms

Kasuni Abegunawardana

8y3.1k.NET

Hi,

I got an error like this.

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

Source Error:

tsmtpClient.Send(tmailmessage);

private static void SenEmail(string from, string to, string cc, string bcc, string subject, string body, bool IsHTML)

{

//create an instant in mail message

MailMessage tmailmessage = new MailMessage();

//assign sender mail address

tmailmessage.From = new MailAddress(from);

//asssign recipiant email address

tmailmessage.To.Add(new MailAddress(to));

//check if cc/bcc is not null

if (cc != null && cc != "")

tmailmessage.CC.Add(new MailAddress(cc));

if (bcc != null && bcc != "")

tmailmessage.Bcc.Add(new MailAddress(bcc));

//assign the subject

tmailmessage.Subject = subject;

//assign the mail body

tmailmessage.Body = body;

//assign the format into mail box

tmailmessage.IsBodyHtml = IsHTML;

//assign the prority of the mail into normal

tmailmessage.Priority = MailPriority.Normal;

//subject encoding by UTF-8

tmailmessage.SubjectEncoding = System.Text.Encoding.UTF8;

//body encoding by UTF-8

tmailmessage.BodyEncoding = System.Text.Encoding.UTF8;

//Create a new instance of SMTP client and pass name port number from SMTP gmail server

SmtpClient tsmtpClient = new SmtpClient("smtp.gmail.com", 587);

//enable SSL of theamtp client

tsmtpClient.EnableSsl = true;

//use delivery method as network

tsmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;

//use the Credentials set to false

tsmtpClient.UseDefaultCredentials = false;

//pass account information to the sender

tsmtpClient.Credentials = new System.Net.NetworkCredential("Email", "Password");

tsmtpClient.Send(tmailmessage);

}

5 Replies

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Suraj Kumar8y ago
When you enable less secure access in your account by login to gmail in that case gmail automatically send a mail to your about intimation to less secure app access. You have to accept that mail as highlighted in the screen shot.

Believe I have already checked and run your code and I was getting the same error but after enabling the less secure app and running your code it is sending mail successfully and the code which I have provided is also sending mail.

Your username should be fully qualified for example, --- [email protected]
Amit Kumar8y ago
Hi Dear , Now a days It is very common issue For solve it you do change the some setting on ur gmail account go to the below link ................https://myaccount.google.com/intro/security .......... .. Once you visit the link you need to modify the Less Secure Apps setting and Turn On access to Less Secure Apps as shown below. The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required
Kasuni Abegunawardana8y ago
I turned on "Access for less secure apps" but still i got an error like previous.

In web config i have added follow lines and i gave my real user name and password too.
Aman8y ago
Since for the security purpose Gmail will by default restrict few apps to access from outside and because of that you are getting this error . So just visit this link https://www.google.com/settings/security/lesssecureapps and "Turn On" the "Access for less secure apps" option. It should help .

If not then sometimes google may block access from the apps if it is getting accessed from some other region (because may be from hosted server). In that case just open the server in that region and try login your gmail from the browser from the same region where your app is accessing your account.

I hope first option will work for you but if not try the second one after both of this it will definitely work.

Let me know if any help needed for the same
Suraj Kumar8y ago
Your code is also sending but you have to First enable less secure app access by the following link

https://myaccount.google.com/lesssecureapps

and then write the actual email and actual password in second last line of your code. Replace Email with actual email and Password with actual password

tsmtpClient.Credentials = new System.Net.NetworkCredential("Email", "Password");

alternative you can follow the below code also to send the mail.

private void SendMail()
{
try
{
using (MailMessage mm = new MailMessage("[email protected]", "[email protected]"))
{
mm.Subject = "Sending Mail";
mm.Body = "Hi Suraj, How are you?";
mm.IsBodyHtml = false;
SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com";
smtp.EnableSsl = true;
NetworkCredential NetworkCred = new NetworkCredential("[email protected]", "testPassword");//Provide here your email id and password from which you want to send the mail.
smtp.UseDefaultCredentials = true;
smtp.Credentials = NetworkCred;
smtp.Port = 587;
smtp.Send(mm);
ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Email sent.');", true);
}
}
catch (Exception ex)
{
Response.Write(ex.Message.ToString());
}
}