Probably referring to OWL plugin. However your admins can allow IMAP access to outlook365 and with tbsync, you get full integration for free. OWL is good tho too
I am my own admin, running my small business so I am user/admin/spam receiver :). I might stick with Outlook for business for the moment. Don't want to mess around. For private use, Thunderbird is chef's kiss .
How does the tracker blocking work? It blocks remote content by default, but does it block tracking pixels when I load images? I also installed the ublock origin addon, but it keeps saying that it didn't block anything
By not downloading anything except text and Html the sender can't tell whether you opened it or not. However, pressing tracked links will track you if you don't have some privacy thingy on your browser.