Hi SarahD24,
Thanks for trying to resolve this on your own. We haven't had any reports about issues with sending emails. If you've sent an email and your customer isn't receiving it, it's worth resending the invoices first. If the emails still don't show up in the sent email tab after resending, check out this link for more troubleshooting steps.
If these steps don't fix the issue, our support team can help further. You can reach them via live chat through our virtual assistant MOCA or create a support ticket via MyAccount.
Cheers,
Princess