The only way that email is down for days for a competent sysadmin is if their DNS is also with AWS, so I assumed that was the case. Assuming that is true, what is weird to me is that, after deciding he hated AWS and left it, that he still kept his business DNS (the most important service there is) with AWS.
replyIf you would have read the article, you would know that the writer had DNS hosted at AWS, would have read why he made that choice and would know of his plans to migrate off.
replyI assumed he just had DNS at AWS, but after re-reading I guess he has DNS _and_ domain registrations at AWS, which would be a special kind of stupid. That's something we were advising customers against already back when cloud wasn't a thing yet to enable fast transfers when stuff goes south
reply(to clarify: DNS+domain at the same service can be OK, as long as you have nothing else there. As soon as you start having other stuff, keep the DNS there, but move the domain registration away. Depending on which domain make sure you have auth keys, access to the admin domain or whatever would enable moving the domain without registrar cooperation. In my hosting days I did my fair share of emergency transfers and infrastructure to help companies get their basics online again after a SNAFU - totally doable to have first mail coming in again within a working day)