I would argue modern MacOS is not “bad software” per se, it’s just nothing to write home about. Back in the heyday you describe, it was innovative and quite spectacular compared to the competition. Nowadays it’s rivals are better featured in many respects, but it still does everything it needs to.
I take it webmail is due to Exchange-based mail?
The €10 I pay a year for Exquilla is worth its weight in gold. It’s about the only thing on my system that’s not FOSS, but I’m not even mad because it works. 9.5/10 would recommend.