Google Duo, the search giant’s video chat app, works just like any other instant messaging app out there and uses mobile numbers as a contact identifier to make calls. And even on the web client, Google Duo will only show contacts whose mobile number is saved and synced with your Google account.
However, Google Duo is now testing the ability to let users find contacts with their email address and start a video or audio call. App reverse engineer Jane Manchun Wong spotted this unannounced feature called “Reachable with email address” in the Accounts section of Google Duo.
The description reads “Let people contact you on Duo with your email address”, which makes it quite clear what this feature is intended for. This tool will definitely come in handy when you don’t have a person’s contact number but happen to know their email address. However, it also leaves the doors open for spammers to misuse it.