How can I associate emails to a lead or contact if their email address is in the "reply to" field?

How can I associate emails to a lead or contact if their email address is in the "reply to" field?

Hi there,
I have clients booking calls using a different system that isn't connected to Zoho.

I get notifications of client bookings from an email address "no-reply@", but the reply-to field is the client email address.

How can I automatically associate these emails to a contact record?

I want to avoid BCC solution if possible.