"Fill out the Facebook signup form using your Rediffmail ID. Hit Sign Up."
You do not need a Gmail or Yahoo account to join Facebook. If you have a Rediffmail email address, you can use it directly to sign up. Here is how to do it in 5 simple steps. create facebook account in rediffmail
While this is technically possible, Rediffmail is an older email service. Facebook's security systems sometimes flag less common email domains. Using Gmail or Outlook is recommended for better deliverability of Facebook’s verification emails. Option 1: Step-by-Step Article (For a Blog or FAQ) Title: How to Create a Facebook Account Using Rediffmail "Fill out the Facebook signup form using your Rediffmail ID
"Can you use Rediffmail for Facebook? Yes. But here is the catch most people miss." create facebook account in rediffmail