Is it appropriate to email a philosopher in Academia about a journal article

Is it appropriate to email a philosopher in Academia about a journal article

Is it appropriate to email a philosopher in Academia about a journal article they may have published, whether it be with a possible criticism or query? This is assuming that the emailer is just a casual reader of said journal, not an academic, with no involvement in a university. Also assuming the email is polite, to the point, not of an exorbitant length, and the emailer is quite sure of his query or criticism.

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