How to solve Google SMTP Server attempt prevent error ?

Before some time, I am working on my ASP.NET Project and Send mail to customer Email Address using Google Gmail SMTP Service Provide, but Google say me "Sign-in attempt prevented" and apear bellow message in my Gmail inbox:

Hi Unique

Someone just tried to sign in to your Google Account ........ from an app that does't meet modern security standards....

And after see message, Just i enable "Less secure apps" and SMTP working Fine and problem solve..

Gmail SMTP Configuration
smtp.Host : smtp.gmail.com
smtp.Port  : 587
smtp Username: your Gmail ID
smtp Password : your Gmail Password
More visit: Google Apps SMTP Setting Official

Less Secure Apps Access URL: 
https://www.google.com/settings/security/lesssecureapps

Send large files on Whatsapp upto 2GB on Android [Rooted Phone must required]

1. Download "Root Browser"

2. Open "Root Browser" and Go to "root" folder

3. Inside root folder go to "data" folder

4. Inside data folder go to "data" folder [again]

5. Inside data folder go to "com.whatsapp" folder

5. Inside com.whatsapp folder go to "shared_prefs" folder

6. Finaly, You see all the files, search "com.whatsapp_preferences.xml" file and click open

7. Open file in "RB Text Editor"

8. Change value 16 to 500 and Save file and close

Done...!