How to config Webmail

I have a domain on bigrock.in and change the name server with cloudflare’s name server. I am unable to use webmail. I found that it’s actually does not find cname records.

https://www.whatsmydns.net/#CNAME/myiqrocks.com

Please help me to solve this issue.

That link is for the CNAME to your main site. What’s the URL supposed to be for webmail? It should have been picked up in the DNS scan by Cloudflare. If not, then check back at your host’s DNS to make sure your Cloudflare DNS entries match the ones at your web host.