True. It can be extended to work also on bigrams instead of individual words, I'm not sure how often this is done in spam filters. For an in-depth explanation

True. It can be extended to work also on bigrams instead of individual words, I'm not sure how often this is done in spam filters. For an in-depth explanation of how it works, I suggest the excellent book from Jurafsky and Martin https://web.stanford.edu/~jurafsky/slp3/4.pdf https://web.stanford.edu/~jurafsky/slp3/4.pdf