Yahoo Mail Notification Is Disabled on an Android
The procedure for getting your Yahoo Mail notifications working on an Android device depends on whether you are using the official client app or a third-party alternative. Notification settings are typically contained with the relevant app, though if you've installed an alternative launcher for your device you may find additional notification settings here.
1 Yahoo Mail Android App
Yahoo offers a free Yahoo Mail app for devices running Android 2.2 or above. If you have this installed and are accessing your email accounts through it, head to the app's own notifications settings page. Tap "Settings" from the app menu then select your email address. On the subsequent screen you can set whether notifications appear in the status bar, and whether they are signaled with a sound or a vibration. If you have several email accounts configured through the app, you can set different notification preferences for each one.
2 Android Email App
The default Email app provided with stock versions of Android uses separate notification settings for each account you add. These notification settings are displayed when you create the account and can be modified at any point afterwards. Tap the app menu button (three vertical dots), choose "Settings" and then select your Yahoo email address. You can switch notifications on or off under the Notification Settings heading and associate a sound and a vibration with them as well.
3 Third-Party Launchers and Apps
If you have notifications switched on in the relevant email app there should be no reason why Android won't display them, unless you've installed a third-party launcher that overrides the default notification settings. These alternative launchers customize various aspects of the Android home screens and interface, and some enable you to change the notification display settings too. If you have installed a launcher, check its individual configuration settings for options relating to notifications. Likewise, if you're using something other than the Yahoo Mail app or the default Email app for Android, check within the app itself for notification options.
4 Email Syncing
If new emails aren't appearing at all within your chosen email app, check the sync settings associated with it. If you've set up the official Yahoo Mail app, check the Yahoo account options from the main Settings app for your device; if you're using the default Android Email app, the synchronization settings can be found under the "Sync Frequency" option within the Email app settings page. You can choose to check for new messages at intervals ranging from five minutes to one hour, or opt to sync messages manually on demand.
5 Version Disclaimer
The information above applies to and has been verified with stock Android 4.4, the latest version of the operating system as of November 2013. If you are using an alternative version of Android or the apps mentioned, details may vary.