I did a search in Mail.app for a keyword I thought might be in the subject line of some messages. It showed me two copies of the same message from last September, a message I had sent to somebody else about a backup script I was writing, e.g., Code: From Subject Date Doctor Q diskbackup Sep 30, 2005 Doctor Q diskbackup Sep 30, 2005 When I clicked on one, I was shown the message in my Sent mailbox. But when I clicked on the other, the message display area had only this:The message from Doctor Q <doctorq@...> concerning diskbackup has not been downloaded from the server. You need to take this account online in order to download it.It's a POP3 account, and always online, and mail is not kept on the server after I pick it up. Furthermore, the message in question is one I sent, not one I received, so it wouldn't ever have been on the server waiting for download. I looked for clues in Mail.app's help, and rebuilt the Sent mailbox to see what would happen, and the symptom is reproducible and remains unexplained. This is not a problem I need to solve, but I'm curious exactly what caused Mail.app to display this message, and under what normal circumstances Mail would be able to identify POP3 messages in a search that have not yet been downloaded.