By default, this will be the same as the "service.listenaddr". The RFE was to allow this to bind to a different address.
If that's what you're looking for,
local.service.http.popbindaddr
is the configutil setting. You may not be able to set this with the normal configutil setting,
./configutil -o local.service.http.popbindaddr -v 1.2.3.4
If so, use the -l (local) form:
./configutil -o -l local.service.http.popbindaddr -v 1.2.3.4