Upon sending invoices to clients, it gives an error as not sent. Email adr is correct and I have a Internet connection

Hi there. I'm here to help you resolve the error that you encounter. 

Here are three possible solutions to resolve issues with sending and receiving emails. 

First, you may need to reset your email address if you recently imported data into QBO

1. Sign in to your QuickBooks Online account.
2. Proceed to Settings ⚙, then select Account and Settings.
3. Select the Company section, then click Edit ✎ in Contact info.
4. Review each email address and make changes as needed.
5. Choose Save, then Done.

Then, you can ask your customers to check their junk mail and spam folders. If the email is still not found, clear it and then re-enter your email address.

1. Navigate to Settings ⚙, then choose Account and Settings.
2. Go to the Company section, then click Edit ✎ in Contact info.
3. Clear the Company email field and enter the desired address as is, even if it appears correct.
4. Select Save, then Done.
5. Send yourself a test transaction.
6. If you still don't receive the email, try using a different email address with a distinct domain.

If the issue persists, it'd be best to ask an IT expert to help configure the server to accept QBO mail server hostnames and IP addresses.

I've also included the following articles for your future reference. It covers subjects like receiving invoice payments and customising forms:

• Record invoice payments in QuickBooks Online.
• Customise invoices, quotes, and sales receipts in QuickBooks Online.

Fill me in if you have additional questions about managing your quotes and invoices in QuickBooks. I'm always here to help. Take care always!