LXR shows that japnese langpack, trunk, /mail/app and /browser/app have these entries. It also shows no code uses these strings. Full bmo comment query shows two bugs contain this string, bug 26526 has a copy of all.js, bug 171082 mentions removing this from Phoenix. Mail had always from the browser proxy prefs. I wish it wouldn't, I wish they could get their own prefs UI, we get lots of bugs in mailnews because it does not make sense. If they are not going to add support in Prefs UI, I think we should remove this.

network.proxy.news /l10n/langpacks/nscp/ja-JP/defaults/pref/all.js, line 491 -- pref("network.proxy.news", ""); /l10n/langpacks/nscp/ja-JP/defaults/pref/all.js, line 492 -- pref("network.proxy.news_port", 0); /modules/libpref/src/init/all.js, line 623 -- pref("network.proxy.news", ""); /modules/libpref/src/init/all.js, line 624 -- pref("network.proxy.news_port", 0); /mail/app/profile/all.js, line 607 -- pref("network.proxy.news", ""); /mail/app/profile/all.js, line 608 -- pref("network.proxy.news_port", 0); /browser/app/profile/all.js, line 441 -- pref("network.proxy.news", ""); /browser/app/profile/all.js, line 442 -- pref("network.proxy.news_port", 0); patch coming up in 205077

RESOLVED/FIXED: