Ref T7199. In the vein of D12231, these options were a bad idea.
- They once served a very narrow, Facebook-specific need (see T1992), except even Facebook only used the Differential setting AFAIK.
- Outside of that special case, they are unused and essentially unusable (generally speaking, they do not meaningfully implement anything modular or replaceable).
- I have no knowledge of any install ever changing these settings, and can imagine no reason why they would.
Moving forward:
- If they really need to, they can fork locally and chagne one line.
- I expect "!actions" to make mail at least somewhat more modular soon, anyway.
- Any derived handlers would break after T7199 and need to be rewritten anyway, so this is just taking advantage of a BC break to do cleanup.