Mail crashing repeatedly NSException "NSInternalInconsistencyException"

Thanks for stopping by the Apple Support Communities, rez2380,

If we understand, you received an error message after the Mail app on your Mac unexpectedly quit. We're happy to help!

Based on what you've described, we would recommend going through the steps outlined in the Apple Support article If an app on your Mac stops responding, closes unexpectedly, or won’t open - Apple Support.

Should you still need help after that, please get in touch with Apple Support directly. You can do that here: Get Support.

Have a wonderful day!

Thanks for getting back in touch, rez2380,

If the steps in the article did not resolve your issue with Mail, you will need to get in touch with Apple Support directly for additional assistance with the Mail app: Get Support

Enjoy your weekend!

I'm having this same problem and it's so frustrating. The exact same error and log. I've contacted customer support multiple times, and I've even went to the Apple store and let one of their "geniuses" check out the computer. I've been everything mentioned above. It's been narrowed down to my business email account - which is the most important account that I have! I'm forced to view my emails on my iPhone - which works fine. Just, one day a couple weeks ago my Mac computer's mail app decided it would crash every time I open it. I hope you find an answer. It's a nightmare responding to all of my business emails via my phone when I have this huge Mac computer in my office.

Hey there! Glad you were able to sort it out! At least for a while. Anyhow not everyone can just delete the V9 folder, as it may contain important mailboxes that are not stored on a server and aren’t saved. It’s best to open ~/Mail/V9/MailData, and just delete the EnvelopeIndex files and relaunch mail, but still recommend having a backup first.

As this failed eventually in your case, is Gmail the only email account you use in the Mail app?

Hi, may I know what you mean by opening internet accounts? did you mean email accounts?

Thanks for the hints. Just deleting a recently added exchange account seems to have done the trick for me. Good thing accessing accounts doesn't have to go through the mail client.

In System Preferences there's a page called Internet Accounts. Look for a rounded blue square with an "@" in it. That's where you can add or delete accounts for email and other services.