IBM To Kernel Maintainer: "You Are An IBM Employee 100% Of The Time"
It's fairly common that many longtime Linux kernel developers use their personal email addresses for signing off on kernel patches or dealing with other patch work, especially when they are engaging with kernel development in their personal time too and occasionally jumping between employers over time while still sticking to interacting with the upstream kernel community, etc. There are also understandably some companies that mandate the use of their corporate email addresses for their official work/patches while now IBM seems to be taking things one step to the extreme...