The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57Client not authenticated to send mail

Question

Unable to send the email from office365 email using SMTP. getting this error each time. I tried many ways, to allow SMTP from the admin center too. Also changed the password too.

Error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 Client was not authenticated to send mail. Error: 535 5.7.3 Authentication unsuccessful [PN3PR01CA0040.INDPRD01.PROD.OUTLOOK.COM 2023-05-18T11:19:25.007Z 08DB572806B55A65]

var smtpClient = new SmtpClient("smtp.office365.com", 587);
                smtpClient.UseDefaultCredentials = false;
                smtpClient.Credentials = new NetworkCredential("[email protected]", "xxxxxx");
                smtpClient.EnableSsl = true;
                smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
                smtpClient.TargetName = "STARTTLS/smtp.office365.com";

                // Create the email message
                var messageMain = new MailMessage();
                messageMain.From = new MailAddress("[email protected]");
                messageMain.To.Add("[email protected]");
                messageMain.Subject = "Hello from ASP.NET MVC";
                messageMain.Body = "This is the body of the email.";
                smtpClient.Send(messageMain);