This Customer/Project email issue has been reported to QuickBooks by MANY individuals and QuickBooks support refuses to do anything to correct this long-term issue.
When using the "Projects" feature, email addresses from the Customers profile will NOT populate correctly regardless of what you do, how you format the email address in the customer profile or update the most current past invoice.
This "bug" is causing our Customers to not receive invoices and this is a very basic feature of such accounting software.
I too spent 2 hours sharing my screen with level 1-2 and 3 support and they all recognized the problem but advised me that there is nothing wrong with the software since I can manually enter email addresses as I create each Customer invoice....YES....enter email addresses manually....why then use QuickBooks software???
IF you utilize Projects or client sub-accounts for your business, QuickBooks is NOT the software to use for your busyness as this long standing email issue prevents all your clients from receiving your companies invoices.
Wish I was aware of this before I switched to QuickBooks as I would have chosen another accounting software company.
Spread this message until QuickBooks resolves this issue so other business do not make the same mistake we did.