Hello there, @vikas4. Welcome to QuickBooks Community! I'm very eager to share some workarounds and direct you to the right direction of support to get this error message resolved in QuickBooks Online.
I realize the necessity of getting this handled as soon as possible in order for this error to be fix.
At this time, we have an open investigation (INV-67106) for this exact issue you stated above. This has been raised with the banking engineers to understand why this unexpected behavior is happening. Rest assured, our engineers are working on a fix.
If you're using the QuickBooks Online trial version, emailing invoices, sales receipts, and estimates is limited to 100 times only. As a result, you're getting a message prompt. To fix this, I recommend completing your subscription.
If you're already subscribed, I'd recommend reaching out to our QuickBooks Support Team to add you to the list of affected users. This way, you’ll receive a notification when a fix is available.
You can check this article that'll help you send estimates to multiple email recipients in QBO.
Stay in touch if you have any other questions or concerns with QBO. I’ll be right here to answer them for you. Enjoy the rest of the day.
