This sounds like the type of thing FairEmail might have as an option. You could also have your email server change the fancy name to an ascii name so any client would display that.

FairEmail has this option under Display -> Show names and email addresses

By default it's names only for the compact header, but if you expand the header (little down arrow at bottom of header) it shows both.

But, it is still not a default always all fields of an email address that we all need to have to help end-users make an inform decision as to whether it is spam or not.

A reasonable compromise I've seen in some clients in the pass is to show just the display-name when the from address is in the address book and the FQEM along side it otherwise.

Showing the FQEM is of less help than one might think because people often scan over it in a list.

A list is never in the From: field. But a FQEM’d From: is most definitely helpful in the truthfulness of its source.

A FQEM’d list in Cc: or To: still remains very helpful in gauging the spamminess of that email.

Is the "FQEM" the punycode version to prevent visual domain collisions?

I am asking, because "fully-qualified email address" is unknown to google, the only result mentioning it on ddg is Bookshelf documentation by Oracle: https://docs.oracle.com/cd/B40099_02/books/SSSE/SSSE_Configu... and that was utterly useless.

All results I checked are about fully-qualified domain names. Alternativley, is a FQEM one that uses a FQDN?

It is a new acronym term in attempt to break free of the spam industry stranglehold on spam.

You should also know who you are getting your email from instead of trusting other people putting in "their" name in the encoded-words (outside its addr-spec).

https://datatracker.ietf.org/doc/html/rfc2047

Or you could say that FQEM, if phonetically pronounce, is an apt and memoriable acronym for a new but easiest-to-implement anti-spam measure.