Clean Install is Not Using Existing Mailboxes in Mail Folder

[parkds]

Hello,
I recently did a clean install on my MacMini to the last version of Mojave so that I could have a fresh start as I got ready to migrate to Catalina, purging un-needed 32bit apps in the process.

Using a backup of my Mac, I transferred my old ~/Library/Mail folder to my User folder. I also transferred my preferences file. After restarting my Mac, I launch Mail but instead of loading my old mailboxes, it is creating 2 new mailboxes. It is treating those as the only mailboxes the application sees and is completely ignoring the existing data. My offline mailboxes are not showing up and my iCloud connected mailbox is re-downloading everything from scratch.

Would love so advice about what is happening and how to resolve. I have archives of emails going back 25 years, so I would like to get all of my mailboxes to load. This method has worked perfectly for me in the past so I am just a bit confused about the issue.

Thanks so much!

 

[Brian33]

Apparently Mail.app needs something other than what you transferred. Maybe there's more than one preferences file? I don't know.

If it were me, I'd delete the user & its current home directory on the new Mac, and replace it by using Migration Assistant (on the new Mac) to transfer the user from your backup. You can migrate an individual user by unchecking the various other categories. I.e., you don't have to migrate all the apps and so forth. IIRC you can also pick and choose which of the user's subdirectories you want to migrate.

I did a fresh install of Mojave and used Migration Assistant from my High Sierra backup. All my mail accounts came through the process OK. Although I did migrate computer settings and other files also, I don't think you need to do that to get a user's Mail account set up.

 

[hideous cheese]

I always clean install a new OS version (although have stuck now with High Sierra), but I found the best way for me historically was

(1) unbundle any nested folders
(2) export each to desktop as .mbox
(3) import these individually into clean OS
(4) re-nest if that’s your thing.

I recently did a clean install of HS and that was my process from a clone