@vishnuu Welcome to the Netlify community.
There are two ways to use Gmail with a site on Netlify.
The first is to use your Gmail e-mail address (such as, vishnuu@gmail.com) as the contact address.
The second is to use Gmail using a custom domain name (such as www.vishnuu.com). To do this, you must set up Gmail to recognize that you want it to handle the e-mail from vishnuu.com. Once you do that, Gmail will provide you with the information to make five DNS entries to direct e-mail to Google. You make these entries at whichever is handling the DNS for your site, whether it’s your registrar (such as GoDaddy) or through Netlify’s DNS. It works either way, but you must have a custom domain name and have everything set up with Google first.
You can find more information here: