All invoices and estimates have email delivery failure message coming up, I have verified email etc.

Hello there, Jack. Let me give you insights on why you can't successfully send an email of your invoice and estimates.

Before digging into your concern, I'd like to ask what error you received when sending an invoice and estimates. You may attach a screenshot so I can get a clear picture of your current situation and supply the needed assistance to resolve this.

In the meantime, we can perform some troubleshooting steps. The browser's cache can become filled and cause issues when working your QuickBooks Online (QBO) account. I suggest running QBO in a private or incognito browsing mode to help your computer run optimally and regain some storage space to continue working seamlessly.

See these keyboard shortcuts to open a private window:

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

For a detailed step-by-step process in clearing your cache, check out this article: Clear cache and cookies to fix issues when using QuickBooks Online.

On the other hand, if your customers are not receiving your sent emails. We can fix it by resetting your email address. Here's how:

1. In your QuickBooks, go to Settings, then select Account and Settings.
2. To the Company section, then click Edit in Contact info.
3. Check every email address and make changes when needed.
4. If done, hit Save, then Done.

For further instructions on how to fix email delivery issues, please refer to this link: 3 solutions for when customers aren't receiving your emails. 

Moreover, scan this article as your guide when sending a sales form to multiple email addresses: Email a sales form or report to multiple email addresses. 

We'll be happy to see you here again. Comment below if you have other questions about invoices and estimates. Happy holidays!