Email rejected per DMARC policy for yahoo.co.uk

Email rejected per DMARC policy for yahoo.co.uk

My daughter has recently been getting error message when sending e-mails to me which are re-routed via Namecheap.  The full error is:

< myname@zoho.com> (expanded from < myname@mydomain.com>): host
   smtpin.zoho.com[204.141.32.120] said: 550 5.7.1 Email rejected per DMARC
   policy for yahoo.co.uk

Can anyone explain why this is happening and what we can do about it.

I also believe that we have lost e-mails coming from yahoo.com but I don't have any evidence.