outlook issues in code

We have a server (multi-session) where multiple users login using their own credentials and run a custom application. This application has some Outlook Integration code (Exchange Online) and Outlook per se is logged in using a service account. Everything works perfectly fine but when the server gets rebooted planned/unplanned, Outlook Integration fails and we manually have to login into the server first using service account, start Outlook and finally log off. After that all users can again run their application successfully with Outlook Integration. We tried to create a scheduled task that starts the Outlook process with service account credentials but that doesn't seem to be enough as it doesn't login the user. Is there any way to automate this so that we don't have to login and start Outlook manually after server gets rebooted or point us in the right direction.