Why does Mail app keep crashing on my Mac mini M2?

I bought a new Mac Mini last year, its an M2 8gb running Sequoia (but have had the same problem on all OS), and have no end of issues with the built in Mail app.

I'm in Sales, so do have a large amount of emails (around 100,000) but surely the Mini should be able to cope? The outgoing 2015 iMac it replaced still has no issues (and has over 250,000 emails on it!).

It constantly hangs, does not show emails as read once you've clicked on them, you click reply but it crashes, all manner of issues.

Is my Mac Mini not powerful enough for my email needs or is the app inferior and if so what should I be using?

Thanks

[Re-Titled by Moderator]