Is there a way to increase the number of emails in a customer account ?

Hello there, @mukul-bagla-squa. I'll be happy to share some information regarding your concern about the email limitation in QuickBooks Online.

You can enter multiple email addresses in the customer information as long as it does not exceed 100 characters, which includes the comma and spaces.

Here's how: 
 

1. Hover your cursor over Sales, then choose Customers.
2. Select a customer.
3. Click the Customer Details tab, then select Edit.
4. You can enter the email addresses in the Email field up to 100 character including the comma and the spaces.
5. Then select Save.
    

For more details about the limitations, check out this article: Email a sales form or report to multiple email addresses.

Since you want to add more email than the expected limitation, I'd suggest sending feedback directly to our product engineers to get this fixed.

Here's how:
 

1. Go to the Gear icon.
2. Choose Feedback.
3. Enter your comments or product suggestions.
4. Then, click Next to submit feedback.
    

You can visit our QuickBooks Online Feature Requests website to track the status of your submitted feedback.

If you want to email or print multiple invoices, sales receipts, estimates, and other sales forms, you can click here.

Please let me know if you need anything else or if you need more clarification about the email limitations. I'll get back to you as soon as possible. Stay healthy!