Is there a way for Zoho to check / error out when a new lead comes in with an email address that is already present in the Contacts Module?  We convert our leads into contacts at a certain point in the sales process and occasionally we have that same customer come back through our website and enter their information again in our contact form which feeds into / creates a lead in the Leads Module.  The new lead will only error out if the original lead hasn't yet been converted?  

Is there a setting that can be updated to allow the leads module to reference other modules before creating a new lead and error'ing out as a duplicate if that new leads' email exists somewhere else in the CRM?

Thanks!