Comment by LinuxBender

Some vendors allow fallback / secondary email addresses. There is a process for getting a domain back. I've never been through it but I hear it is painful and not guaranteed.

My process is to pull all emails off the server daily so that if I lose my email account or domain then instead of trying to switch back to my self hosted solution I just get a new domain, a new email provider and update them in each vendor if I still can. In some cases it will require getting on the phone with someone but I do not have much of a digital footprint. I have cut ties with most vendors that are not within a 5 minute drive. The exceptions being the IRS and Amazon, both of which I could live without and I have secondary contact info in the IRS system plus they like money so they will help me.