I can see an advantage to providing that option, but I think it should be sure to clarify that the email addresses of any members who post cannot be hidden from group members who are subscribed via email.
Also, the display in the list of members without a display name seems problematic. Would you just leave them out?
It's also a little unclear what's meant by "those without the correct permissions." I would leave that out entirely and have it say "Subscribers, but mask email addresses." Otherwise, you're basically implying that some subscribers could see more than some moderators, and that sounds like a mistake.
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