Hi Flash890,
Checking your email on another device was a great isolation step to take. Let's focus on your iPhone. If you haven't done so yet, restart your iPhone. Although simple, this step can help correct some unexpected issues. It's also a good idea to make sure your iPhone is running the latest iOS version. Updates often include fixes, and updating can also help with overall performance: Update your iPhone or iPad. If an update is available, be sure to create a backup before installing it.
If the issue persists, another isolation step you can take is to connect your iPhone to another network. This will tell you if the issue is somehow related to the network it's connected to currently.
If you need more help, reply with the answers to these questions:
- If you have more than one email account set up, do you notice this issue on the other accounts as well?
- Are emails from a specific sender affected?
Regards.