Can't Rebuild Mail

Hey FatMacUserSince1984,

If the emails you saved locally On My Mac are stored in a .mbox format, you could cancel the rebuild, remove the account, add it back to get back what's on the email server and then import the saved mailbox to get the On My Mac emails back onto your Mac.

If they're not in .mbox format, we'd suggest reaching out to Apple for further support on this matter using the following link: Get Support

For more info on importing backed up mailboxes, check out these steps:

Import mailboxes

1. In the Mail app  on your Mac, choose File > Import Mailboxes.

2. Select a source in the list, read the information that appears below the list, then click Continue.

• If you’re importing a mailbox exported from Mail or a folder in the ~/Library/Mail/ folder on another Mac, select Apple Mail. To get to the Mail folder on a Mac, click the desktop to make sure you’re in the Finder, press and hold the Option key, choose Go > Library, then select the Mail folder.

• If you’re importing messages from a Windows or UNIX computer, select “Files in mbox format,” then locate the folder containing the files.

3. Reorganize the imported messages, if you like.

4. The messages are in a new mailbox called Import in the Mail sidebar. You can drag folders and messages from the Import mailbox to new or existing mailboxes, then delete the Import mailbox.

This is outlined further in the Mac Mail User Guide here: Import or export mailboxes in Mail on Mac - Apple Support

We hope this helps out.

Take care!

Hello FatMacUserSince1984,

We have a great troubleshooting article for this that might help with the issue you are experiencing. Please take a look at it here: If emails appear to be missing in Mail on Mac - Apple Support. Please follow this guidance and perform any steps not already completed:

• "If you use more than one email account in Mail, make sure you’re looking at messages for the correct account.
• If you sorted messages, they may be in the list but not in the order you expect.
• If the missing emails are from a specific person or group, check whether you blocked messages from them.
• If you use rules, they may have moved messages to other mailboxes. Try searching for the messages.
• Check the account’s Recovered Messages mailbox, if available in the Mail sidebar.
• Quit Mail, then reopen it.

If the problem persists, you may need to rebuild a mailbox.

If you set up Time Machine to back up files on your Mac, you can use the backups to restore content that Mail downloaded (based on options set in Mail and on your Mac). See Restore items backed up with Time Machine."

If the issue persists, further assistance may be needed. We want to make sure you reach the right team for help with your Mac mail concerns, so we recommend that you contact Apple Support directly. Depending on your region, you may be able to reach them here: Apple Support.

Thank you for participating in the Apple Support Communities and have a wonderful day.

Hey FatMacUserSince1984,

Thanks for getting back to us with that additional information, it’s appreciated.

Let’s see if the issue happens when you set up a new user account. It cannot be one that’s already available on your Mac. It can either be a simple User account of an Administrator account. Here’s how: Add a user or group on Mac - Apple Support 

Once the new account has been created, log out of your current account, then log into the new one. Once there, set up the email account that’s having problems and test the issue: Add email accounts in Mail on Mac - Apple Support

If the issue also happens in the new account, you’ll want to test the login items on your Mac: Remove login items to resolve startup problems on your Mac - Apple Support

If you’re still not able to use the Mail app in either yours or the new account, and since it also happened when your Mac was in safe mode, per the article, see if reinstalling the macOS resolves the issue:

How to use safe mode on your Mac - Apple Support

How to reinstall macOS - Apple Support

Please let us know the results when you're able.

All the best.