Not getting email from a specific source

Not getting email from a specific source

I'm able to get some email sent to my Zoho Mail account, but there is one sender that isn't making it. We've got a form on a Wordpress site hosted on Bluehost that sends an email to us. When we direct this form to a @gmail.com account it's received, but not when directed to our Zoho mail account. We're able to get emails from other sources. We don't see the email in our spam folder or inbox.