I'd like to run Ubuntu with an application suite that tightly integrates IMAP/SMTP/CalDAV and has a web interface. Citadel and SOGo look promising. Any suggestions?

Go to Calendar settings

In Outlook on the web, select the Calendar icon.

At the top of the page, select Settings  to open the Settings pane. In the Settings pane, you can change the time zone, date format, time format, and first day of the week.

If you want to change a different settings, use the search bar to quickly find what you need, or select View all Outlook settings.

 

Regards,

Peter