Hey there Elliott Brown,
We understand the emails are not affected across the board, and they work on other devices. Let's see if we can narrow down what might be causing this on your Mac.
Since it works on your iPad and iPhone, let us know if it still works, if you disable cellular data, and use the same Wi-Fi network your Mac is connected to. If not, there may be a network issue at home.
- If only a certain account is affected, try removing that account from Mail and adding it again: Log out of or remove email accounts in Mail on Mac. In the Mail app on your Mac, choose Mail > Settings, then click Accounts.
- Select an account, then click the Remove button.
Add the account back and let us know if you run into any errors. That will help determine if there are other steps to take. If the issue continues without error, reach out to Apple Support for further assistance: Contact Apple Support.
Take care.