Having run my own mail server for over a decade, I have yet to have a single time where the server responds by Permanent error of accounts not existing and with

Having run my own mail server for over a decade, I have yet to have a single time where the server responds by Permanent error of accounts not existing and with email bouncing. Losing incoming email is pretty much the worst case scenario when it come to configuration errors. It about as bad as not having backups, in that both cases results in unrecoverable loss of data.