Hi not real sure whats going on but besides email at our main office we also have a server at a remote data center that sends email up to Office 365. Its from a web app and the email is relayed via script to Office 365 for delivery. The issue is when we send a bunch of email out at the same time the app gets this error message from Office 365
451 4.7.500 Server busy. Please try again later. (AS780081)
Any clues? Thanks!