Is anyone having email issues sending

Yes - the "Delivery Server Down error." But the recommended solutions per the QB article don't solve the issue. Was fine yesterday; issue just started this morning. Happening with a customer who I've invoiced the exact same way for 2 years. Have seen at least 2 other users post about this issue on a separate thread (so far).

Hi, trathje. I appreciate you for coming back to the Community. I am pleased to tell you about the email-sending problem in QuickBooks Online. 

We're aware that some QuickBooks Online users are currently experiencing the Delivery Server Down error, causing the inability to send invoices. Our engineers are working diligently to fix this as soon as possible. 

You may want to check for updates about the error. Check out this link: https://status.quickbooks.intuit.com/.

In the meantime, you can send your invoices manually outside of QuickBooks. To do that:

1. Open your transaction, then select the Print or Preview icon.
2. Tap on Download, then save the file.
3. Attach the file to your email, then send it to your customer.

Check out this article to learn how to personalize and add specific information to your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.

We appreciate your understanding and patience. Just click the Reply button or post in the Community again if you need further assistance with any QuickBooks-related concerns. Take care!