Our office has converted over to Office 365. In the older version of Office you could send an email FROM any valid email on the system. With Office 365 this does not appear to work. We have an app that sends out all the emails from users. With this app we specify the FROM as the user who sent the email. This worked until we moved to Office 365. Now I am getting an error saying "SendAsDeniedException.MapiExceptionSendAsDenied". Does anyone know how I can make the EASend control send from any account?

Hi, you need to assign SendAs permission like this:

https://docs.microsoft.com/en-us/office365/admin/create-groups/allow-members-to-send-as-or-send-on-behalf-of-group?view=o365-worldwide