This issue may also be attributed to only one of your email accounts. Of course, I'm assuming that you have more than one configured in the Mail app. If so, I would suggest repeating John's procedure, but this time after the Mail app opens, temporarily disable each of your email accounts. Then shutdown, and then, restart the Mail app. If it does not crash with none of the accounts enable is the first step.
Now, enable one of the accounts. It doesn't matter which one. Shutdown & restart the Mail app. Try accessing the Inbox for that account. If it crashes, you narrowed down which account would have the problematic email(s). If it doesn't crash, leave that account enabled, and then, enable another one. As before recycle the app and try opening the Inbox until you find the account that is the culprit. Let us know your results.