Hi, we have intermittent issues where other mail servers reject the mail for DMARC policy reasons.

We have heard responses from your zoho teaminbox support to contact the other mail providers, where the other mail providers are microsoft (enterprise) as well as 163 (enterprise). I do not believe that these other large mail hosts are having problems. 

1. Does Zoho Teaminbox offer SPF? I only see DKIM in my deliverability panel. 

2. Can teaminbox provide evidence that DKIM was relayed properly. 

I think given that two major global (top ten globally) are facing problems with zoho's mail delivery, it is unlikely that it is a problem with these other parties.