The issue for me seems to have been fixed. I've been using QuickBooks online for over a year (desktop prior to that); I have never had an issue before recently....

I received a message that the issue was resolved but the issue still exists. Is there an eta on the fix?

Thank you for the advice. I did speak with support and they gave me a case number. Looks like the issue is currently being worked on. Hopefully, it'll be fixed ...

I am also having this issue. It started 5/8. I copy myself when invoices are sent. I am getting them but my customer is not and they show as an error ("bounced ...