There has been a significant increase in "undeliverable" invoices. These are customers we have been invoicing for years with no issue and their email address is still valid, we verified by sending them a direct email from our email address. QuickBooks is well aware of this problem and STILL has not resolved this. I don't think your users should have to continually submit a ticket for help. This issue needs to be FIXED! Your users are not able to collect money timely.