Can you briefly explain what it is that you like about Outlook? I've had to use it at corporate clients, and I really detest it. The interface seems to suffer from that same ribbon-nonsense that Word suffers from. Its search is poor and slow. It offers very few display customization options. The calendar in particular is horrendous, I can't even seem to select a time block by clicking/dragging the way I've been able to do in Thunderbird for (probably) 2 decades.

Or maybe you're talking about needing Exchange integration? I don't know what the state of that is on Linux these days.