You must have a smarter toaster than I do. My toaster is a completely deterministic mechanism that knows nothing about my past toasting experience, nor makes any inference about future toast.

A spam filter:

- Is provided historic information about the problem

- Learns from this information to construct a basic model of language

- Is then provided unseen information

- Then makes a probabilistic decision based on a degree of uncertainty.

The exact model behind the spam filtering can be extremely simple (naive Bayes) but could easily (and probably will without you even realizing it) expand to include things like GPT.

A spam filter is making decisions under uncertainty with new information based on patterns it learned from previous information. If this doesn't fit your definition of "AI" then I think if you understood what was happening under the hood I don't think you would consider GPT to be AI either.

If you toaster does learn your toast preference over time from your toasting behavior (unlike mine) then I would consider that AI as well.