problem spam filter

Dear Zoho,
I have an error with the spam filter.
All the emails sent by our e-commerce platform (from office@papeto.ro ) to office@papeto.ro go into spam.
The platform sends automatically a notice by email when a new order is made.

I put the domain (the same domain registered under zoho mail) in the white listed domains. I put also the email office @papeto.ro , still the emails are going into spam.

How can we fix it?
It is very important for us that these emails not to go in spam.

Thanks,
Papeto