Be able to change default email address on yahoo mail
They should update yahoo email website and app to be able change default email address without the need of making another for people that still want to keep using the same account for yahoo mail.
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Yahoo usernames are unique, so this action is not permitted. However, you can create disposable email addresses if you don't wish to create a new account. More info here: https://help.yahoo.com/kb/SLN28815.html