I can completely relate to it. It’s always a bad experience when something like this happens. Stephen.

I have other troubleshooting steps that you can perform when you experience this crashing issue. 

Most QuickBooks users encounter QuickBooks crashes when emailing invoices. This usually arises when emailing customers or clients and happens after pressing the OK button. The error even continues even after performing various measures like using the diagnostic tool, renaming, updating, or repairing the file.

We can try these solutions to make sure it fixes the issue. This way we'll be able to follow a systematic process that we can use to locate the cause of a fault and correct relevant if this is something to do with the hardware and software issues essential to successful resolution.

But first, ensure to update QuickBooks Desktop for better security of data, gives error-free user knowledge, and helps resolve difficulties to some common security loops and bugs. Then, update Microsoft Outlook. This way, you'll be able to set up a mail profile and able to connect to a mailbox. I've outlined the steps to show you how to update:

1. In Microsoft Outlook, go to File.
2. Select Office Account, then Update Options.
3. Select Update Now.
   

Once done, you can set up Outlook as the default mail app and add an email account. After that, you can now toggle the mail settings. To give you a clearer picture, you can also take a look starting from Solution 3 of this article to make sure you've followed the correct process: Crash: Com Error In QuickBooks Desktop.

Moreover, once everything will start working again, you can now process payments in QuickBooks Desktop and learn when you will receive the payment. Read this article for more details: Take And Process Payments In QuickBooks Desktop.

Drop your reply below if you have further questions when emailing invoices. I'm always here to help you anytime.