I set up a domain with Namecheap
I set up a private email server also Namecheap on that domain.
I changed nameservers on Namecheap which I got from Cloudflare
I copied all DNS records off Private Email email service from Namecheap to Cloudflare
as mentioned on the page
https://www.namecheap.com/support/knowledgebase/article.aspx/9967/2176/how-to-set-up-dns-records-for-namecheap-email-service-with-cloudflare-cpanel-and-private-email/#pe
But it sends emails and does not receive emails.