Configuring the Mail Server to Use Yahoo!
You can refer to this article when you want to configure a Yahoo Account for Mail Notifications in Bitbucket Server.
Go to the
Mail server configuration in the
Configure according to your needs:
Account Security settings for Yahoo
If you are running in to authentication issues even after entering right credentials, please make sure you make changes to account security settings. Go to settings->Account Info->Account Security and enable "Allow apps that use less secure sign in"