The only relevant question is:
"Will the investigator use ... information ... obtained through ... manipulations of those individuals or their environment for research purposes?"
which could be idly thought of as "I'm just sending an email, what's wrong with that? That's not manipulating their environment".
But I feel they're wrong.
https://grants.nih.gov/policy/humansubjects/hs-decision.htm would seem to agree that it's non-exempt (i.e. potentially problematic) human research if "there will be an interaction with subjects for the collection of ... data (including ... observation of behaviour)" and there's not a well-worn path (survey/public observation only/academic setting/subject agrees to study) with additional criteria.
The only relevant question is: "Will the investigator use ... information ... obtained through ... manipulations of those individuals or their environment for research purposes?"
which could be idly thought of as "I'm just sending an email, what's wrong with that? That's not manipulating their environment".
But I feel they're wrong.
https://grants.nih.gov/policy/humansubjects/hs-decision.htm would seem to agree that it's non-exempt (i.e. potentially problematic) human research if "there will be an interaction with subjects for the collection of ... data (including ... observation of behaviour)" and there's not a well-worn path (survey/public observation only/academic setting/subject agrees to study) with additional criteria.