[hkbwvjho] Era name

In order to avoid filling up a namespace with many users, for example, user@domain for emails, add an "era name", e.g.,user@era.domain.  This might be most useful for university email accounts.

Inspired by the Japanese calendar.

What are some interesting ways to demarcate and name eras?  Numerical year is boring.  Perhaps astronomical, inspired by "Age of Aquarius".

Analogous to partitioning time is partitioning space: user@region.domain.  This is already often done, even hierarchically.  But people don't stay associated with a location for very long.