How to save time working with 70gb IMAP email data on local email client?

[IssuesGuy]

I have accumulated 190,000 emails (70gb) over the decades in my gmail account. Besides using gmail on the web, I also use a local mail client (Apple Mail) on my Mac to view/manage my emails. The obvious reason is that when I am writing an intense email that requires looking up data from other emails and cut and paste text/image components to compose, working from a local native desktop client is still a lot easier. Also, full email content text search is available, complete, and responsive. I can find anything dating decades back.

The downside with a local client is that Apple Mail needs to first download all that emails (190k of them, 70gb) to the local hard drive on first setup, which took days.

The frustrating part is over the years, whenever I needed to change Macs (because one breaks down or having issues), doing a new setup on a new Mac or user profile will need to go through this ritual all over again of waiting days to download emails.

Is there an easy way to preserve my 70gb emails already downloaded previously and just copy them to my new Mac to dispense with the downloads again?

 

[BrianBaughn]

Mail is organized by a database that, I'm pretty sure, changes from one macOS version to the next. If you were to use Migration Assistant via a Time Machine backup or directly from the old computer (and I don't recommend doing either via wifi) then the new macOS will know how to convert from the old one.

It's possible that if a user copied the contents of ~/Library/Mail from the old computer to the new computer that, depending on the macOS versions involved, the new computer would be able to cope with it. It's either going to be successful or a total failure.

Now that I think about it I would trust a re-download a whole lot more than a migration and database conversion.