After migrating a client’s website to a new server, I encountered a problem where FluentSMTP and Microsoft Office 365 were no longer sending emails. The solution to this issue was straightforward: I created a new app on Microsoft Azure and reconnected it to FluentSMTP on the website.
By doing this, I was able to restore email functionality seamlessly. This process involved generating new credentials for the Azure app and updating the SMTP settings on the website to ensure secure communication between the server and Office 365.