Sometime back, I was helping a client add some new domains to their email server. Once the changes were made, I started sending test messages to make sure everything was working properly. None of my test messages showed up. Strangely though, other messages were coming through just fine. In fact some of my messages were coming through–just not the ones were I was intentionally trying to test the system.
A little digging revealed that their “network administrator” had created a rule to delete any message that contained the word “test”. Since all of my test messages explicitly said that they were tests, they were immediately deleted.
After querying the staff, I found that someone had decided that by automatically deleting any message containing the word test, they would be able to send test messages to mailboxes without disturbing the person who read that mailbox. Of course this also meant that any test message would automatically become useless for doing any type of real testing because it would be immediately deleted from the system.