Hello, ohmannequin. 

I have an idea on how to fix the Batch action feature so you can email all of your customers again. 

Before anything else, did you encounter a specific error message when using the Batch action function?  More details would help. 

This might be a cache-related issue. This can cause buttons, features, and other webpage content to stop working when it's corrupted or full. To confirm this, use a private or incognito window. Access it using these keyboard shortcuts for each browser:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P

From there, log in to your QBO company as you normally would. Then, use the Batch action feature and email your customers again. If it works properly, close the private window and go back to your regular browser. Clear its cache afterwards. Don't forget to close and reopen it to complete the process. 

Another alternative is to use another supported browser to batch email your customers. 

If you're using the QuickBooks Online Windows app, click the Help menu then select Reset App Data. 

After fixing the issue, feel free to visit our articles if you need help with other processes. They contain guides and important information for specific tasks. Click here to go to our topics overview page. 

I'm happy to help again if you have other concerns with QuickBooks Online. Just post your reply, or create a new thread and I'll get back to you as soon as possible.