Does Kilinet ever loose e-mail?

Lost e-mail is very rare. It could happen if the mail server crashed and the backup failed, but that almost never ever happens.

When people ask if mail was lost, we usually find that there was a human error by the sender. The message came back and they didn't understand that:

it was undeliverable because of a bad or wrong address, or the mail WAS received by the organization but was misplaced by a human (not a computer). If mail is undeliverable then it is returned to the sender -- assuming that the sending and receiving servers are following Internet protocols.

When people have a problem, they often ask, "Is the server down?" We have 7 servers running, one of which is the mail server. Right now it has been running continuously for 39 days. It is turned off for perhaps 5 minutes 2-3 times per year. This year we changed to a bigger server and the change over took 90 minutes.

When a mail server is off or down, mail doesn't get lost; rather, it is spooled (saved) for trying later. At some point the sender is informed that it hasn't been delivered but it is still being tried. After a certain amount of time the mail is returned to the sender if it can't be received by the receiver's mail server. We try every hour, and after 4 hours we inform the sender it is still pending. After 24 hours we stop trying and send it back to the sender as undeliverable.