All Inboxes in Mail is incomplete

Hello Craig MacKenna,

Welcome to Apple Support Communities. Are you experiencing this behavior with both email accounts? Also, are these accounts set up the same on both devices? If so, are they set up as IMAP or POP?

Here's how to find out:

View email account information in Mail on Mac

If they are set up differently on these devices, here's how to change the settings so they match each other:

Change Server Settings in Mail on Mac

In the meantime, check out this helpful link:

If emails appear to be missing in Mail on Mac

We hope this information is useful. Kind regards.

Hey Craig MacKenna,

Thanks for clarifying that for us.

Based on the information you've provided, we would recommend reaching out to Apple Support for additional help at this link here: Get Support - Apple

From that link you'll want to select Choose a product > Mac > Apps & Software > Mail. From there select Continue, and you should see a few options to reach out under the "Contact" section, depending on your location.

Take care.