Evolution

Evolution is the closest thing to Outlook’s full groupware model: integrated mail, calendar, contacts, tasks, and memos, with genuine Microsoft Exchange/Microsoft 365 support via the evolution-ews plugin — shared calendars, meeting invitations, GAL lookups, out-of-office. For corporate Linux desktops in Microsoft shops, it’s frequently the only viable answer.

EWS support depends on Microsoft not deprecating things out from under it — modern auth works but setup can involve organizational-policy friction, and it can’t touch accounts locked to proprietary protocols. The UI is dense and old-fashioned GNOME, heavier than Thunderbird for simple IMAP use. If you don’t need Exchange, Thunderbird is the more pleasant daily driver.