How to consolodate old mailboxes into an accessible archive
I have many mailboxes that date back to 2010. I want to know how to consolidate them into a usable archive or mailbox that can be accessed when desired.
MacBook Pro
Move the entire mailbox to the On My Mac section.
You said you wanted one that could be "accessed when desired."
The only way that is possible is to store it within the Mail Library (On My Mac).
If you actually "Archive" the mailbox, you can't really access it when desired. You would have to import the archive, then you could access the import, but it wouldn't be in the same structure as you archived.
Hence, move the mailboxes into the On My Mac mailboxes so that they can be accessed when desired.