[Exception]
System.Net.Mail.SmtpException: 'The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required.
[Solution]
Enable 2FA then enable app password in gmail account settings. Use the newly created password along with the gmail to authenticate and use google smtp service.
[Exception] System.Net.Mail.SmtpException: 'The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required.
[Solution] Enable 2FA then enable app password in gmail account settings. Use the newly created password along with the gmail to authenticate and use google smtp service.