One thing that always gets me is that LibreOffice doesn't have an Outlook.
OTOH, since both Windows and Mac come with their own clients and Linux has an overabundance of options (sadly, no canonical GNOME mail client - I'd love to have something as simple and direct as Calendar), I guess this would be a wasted effort.
Roundcube + the calendar plugin is the closest I've found to an outlook alike for Linux, if that helps. Bit more complicated to setup, but does the trick.
I tried it, but didn't really like how it worked. What I would love would be some form of imapsync between IMAP (and icalsync for iCal) servers and a local (Maildir?) folder and an app that can view the contents of that local folder as an e-mail and calendar client.
Extra points for managing space by deleting files and keeping some form of pointer to the original content.
And that would not be a small feat, considerung how bad the MS Office 365 UI are. Of course, the LO UI is stale but it does not hide stuff from you based on some weird context decision. And don't get me started on the differences between the functions you find on a given ribbon and the matching "simplified ribbon" (or what it's called.)
Where LO shines in comparison is the sane templating system, numbering scheme (chapters, paragraphs, lists etc.) and the total absence of any assistant that tries to be smarter than you.
OTOH, since both Windows and Mac come with their own clients and Linux has an overabundance of options (sadly, no canonical GNOME mail client - I'd love to have something as simple and direct as Calendar), I guess this would be a wasted effort.