Hi starrboogie,
Thanks for the clarification. Do you have any other mail accounts configured that are experiencing similar issues? If so, does the issue remain when connecting your iPhone to another Wi-Fi network, and when using cellular data?
To isolate the issue further and determine where it lies, you'll want to verify first that you're able to sign into your Earthlink account directly on the webmail client from a web browser. To do this, visit Earthlink's website and attempt to sign in.
If you're able to sign in and view your email inbox on the website, you can verify that the mail settings are correct in the Settings app on your iPhone. Earthlink can supply the correct mail settings, or you may use the following tool from Apple to the recommended settings:
Mail - Official Apple Support
If you're able to confirm that the settings are correct, and the issue remains, we can recommend deleting the account, and then adding it back in Settings > Mail > Accounts.
It's important to note that deleting a POP mail account from your device will delete messages downloaded on your device. If those messages aren't visible on the Earthlink webmail client, they won't be recoverable.
If you find that the issue persists after adding the account back, you'll want to work with Earthlink directly at that point to investigate further.
Take care!