20+ years with Apple Mail and I'm ready to give up.

Here are my problems, some of them 10+ years old.

1. Sorting into smart mailboxes is inconsistent in every way. If I write a rule to put all email coming from @myattorney.com into a smart mailbox 'myattorney' it will happen that way 80 percent of the time but 20 percent of those emails are left in the inbox, or sorted into another mailbox altogether. Where they jump out to startle me at odd moments.
2. Almost worse, whatever email is correctly identified and sorted into the right smart mailbox will also stay behind. So the original incoming email is in the inbox, and a copy of it is sent to the smart mailbox. I dare not erase posts in the inbox for fear they will disappear completely.

I hope to find a solid email app that will sort email correctly without spewing extra copies randomly into other mailboxes.

I've tried to get answers on these and related questions here in the Apple Community without success. If someone has answers or suggestions about alternative apps that address these problems I would love to hear from you. Many thanks.