the smtp requires a secure connection 5.5.1

i try all the below methods but error still exists:.

http://www.smarterasp.net/support/kb/a1546/send-email-from-gmail-with-smtp-authentication-but-got-5_5_1-authentication-required-error.aspx

http://www.codeproject.com/Questions/751880/send-mail-using-gmail-after-deploy-the-asp-net-web

https://www.google.com/settings/security/lesssecureapps

provide me some solution for this problem.

thanks