Using classic Outlook for Windows in business environments
On the sync issues -if you open and close outlook frequently, it can make it worse. Microsoft is investigating an issue where Outlook doesn't close properly when you have an IMAP account in your profile and this can cause Outlook to have sync issues. There is a registry key to use as a workaround. If you don't want to edit the registry, I have a ready-to-use registry file available
https://www.slipstick.com/doit/AllowLOGOUT.reg
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\IMAP
DWORD: AllowLOGOUTWithoutOK
Value: 1