Thank you for posting here on the Community page, Rueben1.
I also like the idea of automatically detecting custom field data in the subject line of an email.
The feature to automatically detect custom field data in the subject line of an email is unavailable. However, you can manually enter the needed information on each box.
You can try looking for the most compatible third-party applications in QuickBooks Online. Here's how:
1. Go to Apps.
2. Click Finds Apps.
3. Type a keyword in the Search for an app field.
4. If you have found the app you're looking for, just click Get App Now.
You can refer to the following article for more information about personalizing and customizing the appearance of your sales forms in QuickBooks Online: Customize invoices, estimates, and sales receipts in QuickBooks Online.
Post a reply if you have other questions about the subject line of invoices in QuickBooks Online. I'll be around to help you out. Enjoy the rest of the day!
