It used to be that physical mail would be delivered reliably no matter how adverse the conditions were (as in rain, snow, and sleet). My guess is that most of the current generation using electronic mail never knew that the Postal Service had a motto to that effect, let alone knew the words of the motto. As to the service itself, I doubt that anyone believe the motto any more. (Shortly after my wife and I bought out condominium in San Francisco, the Postal Service managed to lost the bill for our annual property tax. I now use Reminders to let me know when I should be receiving it, since I can now go to a Web page to find the amount if the physical mail fails again in the same way.)
On the other hand is electronic mail any more reliable? We have all received "cannot deliver" bounce messages, even when we know that the address we provided is legitimate. This tends to mean that a server died somewhere along the path. Sometimes there is a place to store accumulated messages while a server recovers; and sometimes (probably more often than not) that storage area fills to capacity before the system is running again. Can we count on being notified one way or another, or could the current bounce system fail because of some other server?
Has the Internet become the latest "rotten fruit," just waiting to fall from a tree that has not been properly tended?