Send email with zoho mail unsuccessful

I’ve created a scenario that initially filters for a specific email in my zoho inbox and if a new email is received that meets the filter requirements, I send an email response to the sender.
The sender is coming from a private server and it appears to be filtering any autoresponse - I’m not sure how to overcome this issue. If I simply reply back to the sender it of course goes through with no problem. Any suggestions for a solution?