by If there are issues in sending emails from staging, you may need to change the admin email of the website.
You need to install Change Admin Email plugin to avoid sending notifications to the past admin of the website.
Next, go to Settings > General and change the view from Default to Classic. Before changing the email address, save the original admin email to a notepad or notes app, then change the admin email to a Gmail account (you can use testingonly8873@gmail.com, just ask me if you want to access this account).