@Archie_B From the start of the thread and my original post. I am not a customer, and would be unable to open a ticket. We are a recipient of a large number of Quickbooks customers, various vendors, suppliers, etc. The Intuit/Quickbooks Sendgrid IPs are the root of the problem as others have mentioned. And don't you dare send me the KB article with the IPs again, you'd be the 3rd or 4th person at this point, because the 3 IPs on the blocklist are not in that KB article.