The APTS_EnableCustomEmailAddressLookup property enables you to launch the custom Email Address Lookup pop-up for the Send for Review and Send for Signature functionalities. On this page, you can quickly search and select contacts for the Additional To, Cc, and Bcc fields, if there is a large number of contacts (for example, more than one million). For more details, see Sending an Agreement Document for Review and Finalizing an Agreement.