Sending your estimates with attachments is my priority, @RJ60.
I'd like to provide you with ways to get your QuickBooks software working as it was before.
First, let's ensure QuickBooks is updated to its latest version. Once completed and you're still getting the same result, let's perform the following troubleshooting steps for possible company file damage to isolate the error you've received.
Once completed, let's close and open QuickBooks to make sure all components are updated. You can now try to send a dummy estimate to your personal email.
For additional insights, you may check out these articles:
If the issue persists, I’d recommend contacting our Technical Support Team. A specialist will be able to further assist you via a secured remote access session.
Should you have other questions about creating and sending estimates from QuickBooks Desktop, feel free to get back to us here in the Community. I'm always here to help.