Outlook

many email programs has settings for how far back they are to download mails from the server so a person who had an account for say 20 years do not need to have storage on their local computer for all that data, you can check in the settings about such options

Microsoft Community

I think the point of the link Bob posted is you should be asking questions regarding Microsoft products in Microsoft's support forums. Outlook is not an Apple product.

My advice is you may get faster and more focused support for Microsoft products in the Microsoft communities where all the participants use Microsoft products.