In some cases, it might be nice to have the capability to specifically call for input of a particular person on a revision/task/audit. I'd see this being useful in the following scenario:
A user that is perhaps subscribed to a great many issues many not be paying particularly close attention to some particular subset of those issues. Or perhaps they are, and they go on a couple day bender (or a vacation, not everyone is a raging alcoholic), and come back to a few hundred issue/revision/audit emails and can't be bothered to read through every update that might have happened in their absence to look for questions for them.
The only real way that you can solve this right now is to either:
1. Track them down in person to ask your question.
2. Find their email and ask them to look at the issue.
3. Do nothing and hope they eventually notice.
The way that I'd envision this working one (or both) of two ways:
* Click on their name from the subscriber list of the task/revision/audit, which opens a text box that I can type my question in, and eventually submit.
* (Preferred), I put something like "RFI @wotte: blah blah blah". This would also be useful, for example, in inline comments.
Ultimately, this would result in a different email from the Phabricator installation that would be distinguishable from a normal issue update, perhaps with a subject line "RFI: TXXXX". It might also highlight the object requesting their input in the web view.
Perhaps this could be built using Ponder; by providing an easy way to create a Ponder question that is tied to a particular task/revision/audit item.