MX Plan configuration with Cloudflare

Hello,
I have a domain on OVH, hosting in other company and website that is being cached via cloudflare.

My website works just fine, but my custom e-mails doesn't.
On Cloudflare tutorial, I see that I should add following records:

A mail <- what IP address I should put here to point on OVH MX Plan?
MX mail. <- is the mail. value should work with OVH MX Plan? Shouldn't I put here other value, like e.g. mx0.mail.ovh.net ?

Btw. Outgoing e-mails from custom domain works, incoming one doesn't.