Migration Assistant Is an Option to Consider
You have options for performing the move. The easiest and most often suggested method is to use the Apple Migration Assistant. This method works well, but it has one drawback: Migration Assistant is an all-or-nothing process when it comes to moving data. It copies everything from one Mac to another. However, you may not be interested in transferring everything to your new Mac.
Move Mail Manually
If you only want to move your mail, transfer three items from your current Mac to a new one:
Mail FolderMail PreferencesKeyChain
After you transfer the files, launch Mail on your new Mac. All of your emails, accounts, and rules will work the way they did before the move.
Back Up Data Using Time Machine
Before you move files around, make a current backup of your mail. You can use a built-in or third-party backup application for this. Time Machine is part of the Mac system and is easy to use. To back up to an external hard drive with Time Machine, select Back Up Now from the Time Machine icon in the menu bar, or right-click Time Machine in the Dock and select Back Up Now. If you don’t have the Time Machine menu bar item, install it by opening System Preferences > Time Machine and placing a check mark next to Show Time Machine in the menu bar.
Prepare and Copy Your Keychain Data
Apple Keychain is one of the three items you’ll need to move to the new Mac. With Keychain, Apple Mail operates without asking you to supply all your account passwords. If you only have one or two accounts in Mail, you can skip this step. If you have many Mail accounts, transferring Keychain makes using the new Mac easier. Before you copy the Keychain files, it’s a good idea to repair or verify the file to catch any possible errors. The method you use depends on your system version.
Verify the Integrity of the Keychain Files in OS X El Capitan or Later
If you’re using OS X El Capitan or later, the Keychain Access app is missing the first-aid feature. Instead, use the Disk Utility First Aid tool to verify and repair the startup drive that contains the Keychain files.
Repair the Keychain Files in OS X Yosemite and Earlier
If you’re using OS X Yosemite or earlier, the Keychain Access app includes a first-aid tool that you can use to verify and repair all your Keychain files.
Copy the Keychain Files to the New Location
macOS stores Keychain files in your Library folder. As of OS X Lion, the Library folder is hidden so that you can’t accidentally make changes to important system files. The hidden Library folder is easy to access, and you can make it permanently visible if you want.
Clean Up and Copy Your Mail Folder
Before you move your Apple Mail data, take some time to clean up your current Mail setup.
Apple Mail Cleanup
Copy Your Mail Files
The Mail files you need to copy are stored in the Library folder. This folder is hidden by default in macOS. If you haven’t set the Library file to be visible previously, open it temporarily. From the desktop, hold down the Option key and choose Go in the menu bar. Select Library in the expanded menu. To copy your Mail files to a new Mac or system:
Copy Your Mail Preferences
The last thing you need to copy is your Mail preferences file:
Troubleshoot Keychain Issues
Moving Keychains around can sometimes cause problems. However, they’re easy to correct. When you copy the Keychain file to its new location on your new Mac or system, the copy might fail with a warning that one or more Keychain files are in use. This can happen if you have used your new Mac or system, and in the process, it created its own Keychain files. If you’re using OS X Yosemite or later, you can use an alternative method of getting your new Mac or system to use your existing Keychain files. Instead of copying the files, make use of iCloud and its ability to sync Keychains between multiple Macs and iOS devices to achieve the same results. If you’re using OS X Mavericks or earlier, the process is a little more involved.
Troubleshoot Mail Issues
Occasionally, you may run into a problem when you first launch Apple Mail on your new Mac or system. The error message usually says that Mail doesn’t have permission to access a specific file. Make a note of which file is listed in the error message, and then do the following: That should correct the problem. If Mail reports a similar error with another file, add your username to every file in the Mail folder.
Propagating Your Privileges
How to Rebuild Apple Mail
Rebuilding your mailboxes forces Mail to reindex each message and update the list to accurately reflect the items your Mac is storing. The message index and the actual messages can sometimes get out of sync, usually as the result of a Mail crash or an unintended shutdown. The rebuild process corrects any underlying issues with the program. If you use IMAP (Internet Message Access Protocol), the rebuilding process deletes any locally cached messages and attachments and then downloads fresh copies from the mail server. Rebuilding IMAP accounts can take quite a while; you may decide to forgo the rebuilding process for them. You can also try resetting user permissions if all else fails.
Why Moving Apple Mail Makes Sense
Starting over with Mail on a new Mac doesn’t make sense. You probably have years of data stored on your Mac. While some of it may be fluff, other information is important enough to keep on hand. It might be easy to re-create your mail accounts on a new system. Still, it’s not easy to start fresh with none of your older emails available, your Mail rules gone, and Mail asking for passwords that you have long since forgotten.
