Re: I have found Thunderbird to be a superior alternative to Outlook.
Customers of mine that use T'bird rarely have problems. Those using on-prem Outlook have all sorts of inexplicable woes which when identified, fall into these categories:-
(i) Microsoft Updates (ii) a functionality of Outlook has changed between versions (deleted as well as added) (iii) Anti-Malware program interference (iv) mailbox corruption or bloated mailbox size (v) emails going walkabout (vi) winmail.dat issues (vii) licencing issues whilst using the legitimately licenced application.
(iv) and (vi) have decreased substantially in recent years, but bloated mailbox sluggishness has not. Trying to drive Outlook from a third-party program (MAPI) has some bizarre "rules" defining behaviour, which can be painful to satisfy.
Sorry, that was intended to be a succinct list, but the more I thought about it, the more that needed to be added.
One of the big snags with Outlook is the dangers of reinstallation to troubleshoot dire problems, will there be hassle with licencing issues upon reinstallation?