Can i save a sales invoice without entering an email address?

I've encountered the same situation before, suz3.

In QuickBooks Online, you'll get this error when the Send later box is checked under the Customer email field. Let's change the preferred delivery method by following these steps:

1. On the left panel, click Sales and select Customers.
2. Click the customer's name and select the Edit button.
3. Hit the Payment and billing tab, then choose None from the Preferred delivery method drop-down menu.
4. Select Save.

Here's a sample screenshot for reference:

You can also go to the settings to set the delivery method.

Here's how:

1. Click the Gear icon located in the upper right-hand corner.
2. Under Your Company, click the Account and Settings.
3. On the left panel, click Sales, and select the Sales form content.
4. Select Send Later from the Preferred delivery method drop-down list.
5. Click Save and then Done.

That should fix the error when you save the invoice.

If there's anything else you need, you can always leave a reply on this thread. Have a great day!