Several times in the past, after publishing a paper, I have sent email to several people which I thought might be interested in the results obtained in the paper. Usually I have emailed some of the people whose result I was citing in my paper and to people who were working on related problems.
I such a practice ok, or do people consider emails like this too intrusive?
When I did this in the past, some of the people answered to me with a brief email (along the lines of "thanks for letting me know"). In a one or two cases the answer indicated that this person is interested in similar emails in the future, if I have some updates on that particular topic. And in one case I was even asked about possibility of collaboration on some problems.
So from these answers it seems that it was ok. But if there were some people who did not like receiving such emails, they probably did not bother to answer.