Mozilla/5.0 (Windows; U; WinNT4.0; en-US; m18) Gecko/20001025 Netscape6/6.0 10/25 Commercial on WinNT 4.0 SP4. Under Mail Folders, my "Scopus" folder is in bold with (1) in parentheses, indicating that there's one unread messages. Yet I already have that folder open and there are no unread messages, only five already-read ones. I have View-->Messages-->All set. Whether I set view Threaded on/off has no effect.

maybe bug 56707

Another data point on this one, the bug seems to be on local mailboxes, the unread count is accurate on IMAP mailboxes (using Linux Build ID: 2000102921).

Yes, I use POP--thanks for noticing this!

I just did a test, I removed the .mozilla/default/Mail/Inbox.msf file with mozilla not running, then started it up, opened mail and the Inbox folder now has the correct count of unread messages. I still have the old Inbox and Inbox.msf files if it can help.

dup of 32369: "emails: Unread 1 Total 0 - (phantom unread e-mail messages in Inbox)" *** This bug has been marked as a duplicate of 32369 ***

Verified, this is a duplicate of bug 32369 "emails: Unread 1 Total 0 - (phantom unread e-mail messages in Inbox)."