You can email up to 50 customers at a time from QuickBooks Online (QBO), Richard. This helps prevent overload and ensures that Outlook launches successfully.

If you're using QuickBooks Desktop (QBDT), the option to send customer emails is currently not available. However, you can use a third-party app that integrates with QBDT. You can visit the QuickBooks Apps site to find an app that meets your needs.

If it happens that you're a United Kingdom (UK) user of QBO, you can also send up to 50 emails at a time to your customers, just like in the US.

Regarding your second concern, please ensure that your QBO and Outlook are updated to the latest versions. Compatibility issues can cause problems with launching and functioning properly.

Moreover, you can open an incognito window in your browser to access the product with a clean slate. Depending on your browser, you can use the following shortcuts:

• Google Chrome and Microsoft Edge: Ctrl+ Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Safari: Command + Option + P

If Outlook launches successfully, please return to your regular browser and clear the cache for a fresh start. Additionally, switching to other supported browsers could also be worth a shot. 

Furthermore, you can create custom templates for forms, such as invoices, to modify how they look and what information to include.

Keep in touch if you require further guidance about emailing customer transactions or statements in QuickBooks. The Community team is here to help whenever you need it. Stay safe.