I kind of feel the same way, I’m pretty tech savvy, but I think the problem is 99% of folks have multiple devices. I have an M2 mini, M1, MacBook Pro, and an iPhone, and obviously the software only can run on one of them. I know there’s ways to set it up for this to work, but I too felt overwhelmed by the multiple options. Certainly not a set and forget.
I also have six separate email addresses that are managed by Apple Mail / Custom Email domain and I know it kind of works like separate email addresses, but really pushes them all into one account. I think this also messes me up too sometimes. I figured it out. It wasn’t filtering my correct email folder so I check this. It seem to be better.
Biggest issue is most of the time I’m in Europe right now. I’m obviously on my iPhone mostly so as soon as I read all my email messages they can’t be filtered.
You have to decide whether to install SpamSieve on multiple devices or not, but either way the day-to-day use can end up set-and-forget as if it were on a single device. If you have one Mac that’s always on you can just run SpamSieve exclusively there (setup #1). If not, you can just install SpamSieve on all the Macs and uncheck Auto-train as needed in the settings (setup #3).
They are not pushed to one account. SpamSieve uses the standard Junk mailbox, which means that the messages are automatically separated by account but can also be viewed together in the special All Junk mailbox if you want. This has been the standard/recommended setup since macOS 10.15.
Is it possible for you to skip over the spam messages so they don’t get marked as read? Or can you let the Mac mini run while you’re traveling?