Cloudflare Access

Hi there,

I’m using Cloudflare Access feature to secure a subdomain for restricted access.
I have enough license and I tried to add a new domain (e.g. xyz.com) to be authorized to login but the third-party is reporting they are not receiving the verification emails. The existing users are ok. It is each time I add new email addresses or domain, they seem to have difficulty to receive the verification emails. What could be wrong? Is there a delay?

Regards,
Fred