This is a Google Chrome extension that adds keyboard shortcuts to quickly jump between email correspondence on a Request Tracker (RT) Ticket Display page.
This is useful because RT (at least as of version 4.0.6) is not smart enough to properly collapse quoted text in emails.
The shortcuts are control-shift-up and control-shift-down.
It has been tested on Chrome 44.0.2403.125 and RT 4.0.6.
The extension is available in the chrome web store.