Shall I communicate the inclusion in the acknowledgements section?

I recently finished a paper in which I received valuable feedback from two professors (neither supervisors nor coauthors) at some specific points, which ultimately leaded to localized significant improvements. I highly appreciated it and of course I added explicit mentions in the acknowledgements section stating their suggestions.

My question now is: I hardly will see again these professors for a long time. I thought about sending an email to them commenting on their inclusion on the acknowledgements... But then I thought that it should be something understood as obvious, without too much interest for them or even spammy. So, shall I communicate their inclusion in the acknowledgements section? If so, what will be the correct etiquette for such an email?