Yep, it's that setting.

Okay, background: the name of the setting (*Allow viewable email
addresses*) is in fact not correct because email addresses are not
shown to other members (except to admins and *those with permission*
(i.e. admin-like)). The real meaning of the setting is something like
*allow members to initiate a conversation via email*.

Yep, it could be an option to just make it a per-user setting, but
then it would probably be necessary to remove the column from the
mlist (or replace it with PM if not already there or something else,
dunno).

That said, I'm tempted to consider this setting highly redundant: if
people want to communicate via email they can just exchange the email
via PM and then swap to email.
And following that line, I'd be happy to consider its removal.

Dunno what everyone else think about this solution.