How to Fix Wrong Git Commit Author Email Without Re‑committing

Problem Overview

When a repository requires a corporate email address, an incorrect user.email setting can cause commits to have the wrong author email. Instead of re‑committing, the author information can be rewritten in existing history.

Amending the Most Recent Commit

Use git commit --amend with the --author option to replace the author name and email of the tip commit.

git commit --amend --author="NewAuthor <[email protected]>"

After amending, run git push --force if the commit has already been pushed to a remote.

Rewriting Email Across the Entire History

For many commits, git filter-branch (or the newer git filter-repo) can rewrite author and committer metadata. The following shell script demonstrates the --env-filter approach. Replace the placeholders with the actual old and new values, then execute the script from the repository root.

#!/bin/sh
git filter-branch --env-filter '
old_email="[Your Old Email]"
new_name="[Your New Author Name]"
new_email="[Your New Email]"

if [ "$GIT_AUTHOR_EMAIL" = "$old_email" ]; then
    export GIT_AUTHOR_NAME="$new_name"
    export GIT_AUTHOR_EMAIL="$new_email"
fi

if [ "$GIT_COMMITTER_EMAIL" = "$old_email" ]; then
    export GIT_COMMITTER_NAME="$new_name"
    export GIT_COMMITTER_EMAIL="$new_email"
fi
' -- --all

After the rewrite, verify the changes with git log --pretty=format:"%h %an %ae". Force‑push the rewritten history to the remote (e.g., git push --force --tags origin master). Be aware that rewriting history changes commit hashes, which can disrupt collaborators.

Handling Existing Backup References

git filter-branch

creates a backup under refs/original/. If a previous run left a backup, the command will abort with “A previous backup already exists in refs/original/”. Remove the stale backup before re‑running:

# Delete the specific backup reference
git update-ref -d refs/original/refs/heads/master

# Or delete the whole original namespace
git update-ref -d refs/original

Alternatively, you can force the filter‑branch operation with the -f flag.

Alternative Tool: git filter-repo

For large repositories, git filter-repo is faster and safer. The equivalent operation is: git filter-repo --mailmap my-mailmap.txt where my-mailmap.txt contains lines of the form:

New Name <[email protected]> <[email protected]>

References

Git documentation for git commit --amend and git filter-branch GitHub guide: “Changing author info in existing commits”