Verifying a domain configured with Zoho Mail in Zoho CPaaS | FAQ - Zoho CPaaS

After configuring my domain with Zoho Mail once, should I verify my domain again for my Zoho CPaaS account?

Yes, Zoho Mail and Zoho CPaaS are two different services and require separate domain verification. This is because, domain verification for Zoho Mail authorizes Zoho Mail's service alone. A separate authentication for Zoho CPaaS is necessary to use its infrastructure for email-sending. 

Our help page on domain verification will help you get started with it.