Google is now widely allowing users in the US to change their Gmail username (the part before @gmail.com), giving people a way to fix old or embarrassing email addresses without creating a new account.
Users can update their address through account settings, and their old email will remain as an alternate – still able to receive and send messages. However, changes are limited: you can only update your username once every 12 months and create up to three new addresses total.
The feature is fully rolling out in the US, with early signs of availability in other regions, though global rollout details haven’t been confirmed yet.
Source: Android Authority
