MBOX is the de-facto standard for archiving email.
Git grafts is old but still exists
- Git: Grafting repositories
- Collating repositories or grafting earlier history with Git
- How do git grafts and replace differ? (Are grafts now deprecated?)
git replace is the newer mechanism, and can be pushed to others (grafts are local-only)
git filter-branch will flatten any entries in
refs/replace/, making them permanent.
This is a useful technique to join history together.
git subtree is distinct from subtree merges. I’m now more enlightened, although I need to experiment.