For a linux user, you can already build such a system yourself quite trivially with git blame directly, piping it through grep awk and git log to email yourself that list with a cron job.

    (crontab -l 2>/dev/null; echo '15 22 \* \* \* /usr/bin/git blame --line-porcelain abc123.. -- /path/to/file.txt | awk "/^author-mail/ {print \$2}" | sort -u | /usr/bin/mail -s "Authors" user@example.com') | crontab -