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

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.  Exception Details: System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at Source Error: 

Line 73:             smtp.Credentials = NetworkCred
Line 74:             smtp.Port = 587
Line 75:             smtp.Send(mm)
Line 76:         End Using
Line 77:     End Sub

Hello I just download your project and execute your LoginDB to sql server, there is no problem, but the email link is not working it always appear like in the image.. can you help me with the error.....