autofill behavior for adding users to public reply

When adding a new user that is not yet a contact in zendesk autofill suggests a contact even if the email address is cut and paste into the field.  We have already had an agent select the wrong contact because of this which is a risk.  So, if an entire email address is pasted or typed and there is no match I would expect nothing to be suggested.  That would avoid the risk.  Can this autofill logic be altered?