Some questions that need to be considered by a Research Ethics Committee (or an Institutional Review Board) when reviewing research proposals that involve list mining include these: Should those participants in a health related electronic mailing list who were the original sources of messages sent to such lists be regarded as "research subjects"?
These include those pertaining to privacy, informed consent, whether the research is intrusive and has potential for harm, and whether the list should be perceived as "private" or "public" space.
If so, there are issues of copyright and proper attribution to be considered if messages sent to such lists are cited verbatim.
Participants on mailing lists such as electronic support groups may regard themselves as members of an online "community".
To provide an answer to this question, characteristics of various types of communities need to be defined and considered.