I am the administrator of our zoho mail account for datasquid.com.
I cannot send email from Outlook or Android mail client. It is only possible to send email via Zoho web client or Zoho android app.
I got an expert to check my SMTP settings. He confirmed that they are ok and he said this is a common problem which needs to be fixed by Zoho.
I would be greatful if you can fix urgently.