I have a client who I can't send any invoice using the QuickBooks app since last week. It returns an error message “email couldn't be sent”. However, I can send by Gmail.

Hi Igoorr,

Thanks for posting in the Community!

If the customer is unable to receive the emailed invoices from your QuickBooks Online account, I recommend having them add the Intuit email [email address removed] to their safe sender list.

Let's also reset your email address in your company settings. Here's how:

1. Click on the Settings icon and click on Account & Settings.
2. Click on Company tab, and click on Edit in the Contact info.
3. Remove and re-enter your email address.
4. Click on Save and Done.

If there is a CC and BCC email set up, I recommend also removing them first. Here's how:

1. Click on the Company Settings.
2. Click on Sales tab and locate Messages.
3. Click on Edit and untick box for Email from copy (Cc) and Blind Copy (Bcc) new invoices to address and remove the email.
4. Click on Save and Done.

Once done, let's try to send the invoice to your own email address to see if this makes a difference.

If the issue persists, I recommend contacting our Customer Care Team. That way, they can check your account if there is any blocked in placed.

If you need more help in your QBO account, please let me know by adding a comment below.