I just installed AirMail as an alternative to Mac Mail and followed the instructions for activating SpamSieve. Does SpamSieve work with both clients simultaneously? Do I need to do an additional initial training or will it continue to work as previously for either client?
You can freely switch between mail programs or even use multiple mail programs at once. SpamSieve will share its training data and statistics among them, so you do not need to repeat the initial training.