Hi any one know how to add a second email address in my contacts as the invoice address is different from the quote address

Good day, richard139. 

Right now, adding a second email address to your contacts is not an option in QuickBooks Online (QBO). 

I know that you want the email address on your invoice to be different from the quote address. We recognize that each company has unique needs, and I can see how the feature you're looking for would benefit and empower your business. In the meantime, I recommend sending this request straight to our product engineers through feedback. Sharing features and options that you would like implemented is how our engineers look for new product updates.

To send feedback, follow the below steps:

1. Go to the Gear icon at the top.
2. Select Feedback.
3. Enter your comments or product suggestions. 
4. Then select Next to submit feedback.

You may also visit our Feedback forum page. From there, you can see a list of other QuickBooks users who already suggested this feature, as well as the recent updates in QuickBooks.

To learn more about creating an invoice QBO, here's an article you can read: Create invoices in QuickBooks Online.

For your future task, here's a resource that can help you receive customer payments: Record invoice payments in QuickBooks Online.

If you need anything else, please let me know. I want to help in any way I can.