FWIW, MIT's campus computer network (Athena) did this for a long time, because that network was composed of thousands of workstations that did not normally receive mail and all wanted to send mail that came from, for example, <
yandros@mit.edu> rather than something like <
yandros@w20-575-77.mit.edu>. I imagine that they stopped doing this when MIT moved to centralized (Office 365-based, gack) mail infrastructure rather than running their own (with the attendant large reductions in overhead, functionality, stability, etc.) That said, this is probably the exception that proves the rule, as keeping the
sendmail.cf changes up to date was a constant sink for work even before the advent of dkim/dmarc/spf/eieio.