We're seeing number of emails with following error on one of our email addresses:

552 5.1.1 < example-email@oneworldplatform.net> Mailbox delivery failure policy error

Seems to happen only on emails automatically forwarded from our old domain and email provider, before we moved to Zoho. Could you please provide some informations why is this happening and how could we prevent it?

Thanks, and let me know if you need more information.

Here is excerpt of the message:

----- Original message -----

X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20130820;
h=x-original-authentication-results:x-gm-message-state:delivered-to
:to:subject:date:from:message-id:mime-version
:content-transfer-encoding;

X-Original-Authentication-Results: mx.google.com; spf=pass
(google.com: best guess record for domain of
apache@unesc-vm02.inetuhosted.net designates 209.235.249.31 as permitted
sender) smtp.mailfrom= apache@unesc-vm02.inetuhosted.net