Ulrichbrun

It's also possible that there's an issue with client-server communication such that OAB downloads aren't happening.

This prevents Windows clients that are running Office from logging in as required by the authentication process.

This ensures that the system-wide search index service is active and linked to Office 365 apps.

Maintaining a healthy profile is crucial for smooth email communication, better performance and reduced chances of errors or data loss.

Often overlooked, this step can be remarkably effective since it allows your operating system to refresh its processes and resolve any lingering issues that might be causing connectivity problems.

Go to File → Options → Advanced → Send/Receive and set automatic send/receive every 5 minutes for best performance.