We’re spinning up another buddypress community at work and need to customize many of the outgoing emails. This can be done via filters but is kind of tedious and doesn’t make it easy for non-devs to update the messages later. I found a plugin called Welcome Pack which provides a fairly straightforward interface for customizing some of the Budddypress emails, and have started extending it to encompass all of the outgoing mail we need control over (bbpress, wp core emails).
Ideally I’d like to add an Admin interface to link up new filter hooks, but for now I’ve just got a filter function you can use in your theme or plugin. It’s very much a work in progress, right now I’m doing a lot of refactoring to make things a little better suited to our use case. I think by the time it’s done it will save us a significant amount of time that I used to spend hunting down and editing email templates.
You can view my fork of the project on github. If this is a project anyone else is interested in, let me know!