Is there any way to have the estimate number automatically enter on the email subject line when and estimate is sent via email?

Hello, @user87090.

Yes, when you send an estimate to your customers the subject line will display the Estimate Number.  You can check how your send forms preference is set up in QuickBooks.

Here's how:

1. Go to the Gear Icon.
2. Choose Custom form styles.
3. Click the New Style drop-down.
4. Select Estimates.
5. Go to the Emails tab.
6. Review the message that will be sent together with the estimate.
7. Click Done.

I've added these articles to help you learn your ways around managing your sales form in QuickBooks:

• How to Send Estimates, Quotes, & Proposals 
• Set up and use estimates 

Let me know if you have other questions about customizing your sales form template in QuickBooks. I'm always here to help.