The invoices ive sent to my clients via email are not being received? Hasnt been an issue until today?

Welcome and thanks for posting in the Community, @cliffwhite2.

Below are a few possible reasons why your clients are unable to see or received invoices sent in QuickBooks Online (QBO):

• The emails might have been marked as spam. 
• Many email providers use various blocking mechanisms on their servers. Your clients' emails may be blocked by their providers. 

To isolate this, have them check their Spam or Junk Mail folders to verify if the invoices were moved there. If they're unable to see it, try clearing and re-entering your email address in the settings to refresh the system.

Here's how:

1. In QBO, go to the Gear icon at the top right to get to the Account and Settings. 
2. Select the Company tab at the left pane and tick the Pencil (edit) icon in the Contact Info section. 
3. Remove the email address, then re-enter it again.
4. Hit Save and Done.

Once done, try to send a test invoice to yourself to double-check.

For more information, consider checking out these articles:

• Email and customise sales form.
• 3 solutions for when customers aren't receiving your emails.

Please know that I'm only a post away if you have any other issues or concerns. I'll be more than willing to assist. Have an amazing rest of the day!