There are phone switches that were made in 1982 that are still running phone service, including 911 calling, for mid-sized towns. And yes, postfix or Exim or q

There are phone switches that were made in 1982 that are still running phone service, including 911 calling, for mid-sized towns. And yes, postfix or Exim or qmail, once set up, in a fixed configuration like boat only email, could easily run for decades automatically.