Smtp server requires a secure connection or client was not authenticated

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C#

i am trying to send an email from c# code using SMTP.

I am using third party SMTP. (Not using gmail SMTP).
Its login credentials are working perfectly.

but when i try to send send email it is giving me an error.

Getting error message

"Sending fail: The SMTP server requires a secure connection or the client was not authorized. The server response was SMTP authentication is required"


SenderEmailAddress and SenderEmailPasswor are passed to method as a parameter.

I have already tried suggestion found on codeproject but not working for me

What I have tried:

var email = new MailMessage();
var GmailSmptp = new SmtpClient();

GmailSmptp.Host = "mail.xyz.com";
               
GmailSmptp.UseDefaultCredentials = false;

GmailSmptp.EnableSsl = false;
GmailSmptp.Port = 465;
GmailSmptp.Port = 26;

GmailSmptp.Credentials = new NetworkCredential(SenderEmailAddress,SenderEmailPassword);


email.To.Add(EmailTo);
email.From = new MailAddress(SenderEmailAddress);
email.Subject = EmailSubject;
email.Bcc.Add(SenderEmailAddress);
email.IsBodyHtml = true;

GmailSmptp.Send(email);