In Eudora, if you set up your own rules to identify certain emails and send them to specific folders (or spam), those rules process emails once they arrive at the inbox. So they can appear in the inbox for a short period while the rules process them, then are moved.
It’s possible Eudora’s Spam filters work the same way – finding and moving Spam emails from the inbox to the spam mailbox.
I use POP mail, not IMAP, which is important in these discussions. The email fetched by Eudora is the email that’s in Earthlink Server’s inbox. Not the email that’s in Earthlink’s own Spam folder. Eudora doesn’t move any files from one location to another on Earthlink Server because it’s a POP connection. Someone using Eudora for IMAP email could set up filters to move emails from one Earthlink Server folder to another but I’m not using IMAP.
Then, once the email is fetched by Eudora, it gets subjected to client-side spam filters that may redirect the inbound email to any of four dozen mailboxes on my own computer (well, a great many of them don’t get any modern inbound emails; nothing goes into “Inbox Archive 1991-1996” these days; but you get the general idea).
Several days after Eudora fetches inbound email, that email is deleted from server. I leave that cushion time in case I wish to see the email via web mail even after it’s been fetched by Eudora.
I checked Earthlink Server’s Spam folder to see if it had been moved there post facto; it hadn’t. I then checked inside Eudora, which has a massively powerful advanced search (that’s a big part of why I still use it), and no, nothing of that ilk had been received in any mailbox within the last 2 days.
It was showing in web mail (Earthlink Server), vaporized when I tried to open and read it, and was nowhere to be found when I went searching.