Our small mail server is doing OK. Incoming spam is an issue but not a massive problem. Outgoing spam doesn't exist. Once a year the IP ends up on the Microsoft blocklist but using the deliverability form to submit mitigation requests is easy enough and takes half a day or so to sort out.

I'm looking forward to seeing what the Thunderbird team does with Stalwart.

That reminds me I've been meaning to spin up a server, install Stalwart and test it out.