You'll have to check your sales form format, email options, and print and PDF settings to send this specific email to your customer, braytreeandgarden.
Since you're experiencing issues sending notifications to only one specific email, it could be that the form has special characters to it, your online delivery is disabled, or it has a ZIP attached file and exceeds 25 MB.
To resolve this, you can start by opening the form you tried to send and ensure it doesn’t have special characters (! @ # $ % ^ & * ( ) _ - = + : ") in the following fields: Description, Attachment name, Message, Email address, Custom form templates.
After that, go to the Sales tab on the Account and settings menu to review your sales form email option. Here's how:
1. Go to Settings, then select Account and settings.
2. Choose the Sales tab.
3. Select Online delivery, then tick or untick the PDF Attached checkbox.
4. Click Save, then try resending your sales form. 
Lastly, please ensure the attached file is not a ZIP file and does not exceed 25 MB in size. Then, remove any special characters from the file name.
If you encounter other email delivery errors, please see this article for the step-by-step guide on how to fix them: Troubleshooting invoices and payments in QuickBooks.
You may also want to generate sales reports in QuickBooks to determine your best-selling products, gain insights into your buying and selling activities, and analyze your cost of goods.
If you have other concerns, return to this thread so we can help you.