Too many mails in Spam Folder and Mails delivered to ZOHO email adress failed

Too many mails in Spam Folder and Mails delivered to ZOHO email adress failed

Dear Sir or Madam,

I am user of zoho emails. I signed up for zoho with a domain based email adress a few weeks ago. The domain is www.tapethatcollective.com. 

Since a few weeks we have a problem: Some very important emails regularly are delivered to our spam folder. How can we change that? 

Also, currently we have the problem, that sometimes, emails cannot be received by our zoho email address at all. The main email address of our  company is " info@tapethatcollective.com". Currently, everytime we try to send an email from our Gmail adress , it never succeeds. Everytime we try to send an email from our Gmail adress to info@tapethatcollective.com our Gmail adress receives an error notification. It says that "delivery to info@tapethatcollective.com' has failed permanently. Google tried to deliver your message but it was rejected by the server for the recipient domain tapethatcollective.com by mx.zohomail.com. The error that the other server returned was: 554.5.2.3 Mail policy violation Error delivering to mailboxes".

Can you help us to change that?

Kind regards

Milan