When you train a message in the spam mailbox as good, SpamSieve normally moves it back to the inbox. Mac Mail programs do not automatically re-apply rules (or SpamSieve) to old messages, so normally the message will stay in the inbox. However, there are several reasons that a message might stay in the Junk mailbox, “bounce back” to the Junk mailbox, or disappear from the Junk mailbox but not appear in the inbox (in which case you can recover it from the Log window):
When you train a message as good, SpamSieve will purposely leave it in its current mailbox if:
When SpamSieve moves the message to the inbox, a server filter or a mail program on another computer may see the message as new and move it elsewhere. The other computer might think the message is spam and move it right back to the shared server spam mailbox. Or, if the other computer is using a local spam mailbox, it would move the message off the server and into the spam mailbox on that computer. This would make it appear—on the first computer—as though the message had disappeared, but it would still be accessible in the local mailbox on the second computer.
For more information about multi-computer setups, please see the SpamSieve and Multiple Macs section. You can also uncheck Mark it as unread in the Apple Mail or Outlook Training settings to tell SpamSieve not to mark messages as unread when you train them as good. This may prevent other computers from seeing them as new messages.
If the message is moved to the inbox of an account that’s marked as inactive/disabled in Mail’s settings, it will not be visible in Mail because that inbox is hidden. Normally, SpamSieve only moves messages to the inbox of an enabled account, however there is a bug in the macOS 10.15 Catalina version of Apple Mail that causes an error when SpamSieve asks if an account is enabled (FB7035263). Thus, if the disabled account is the best match for the message, SpamSieve could move it there. Versions 2.9.38 and later of the SpamSieve plug-in work around this Mail bug; you can click Install Plug-In to make sure that you have the latest version of the plug-in installed.
You can enable the account in Mail’s settings to view its inbox and find the “missing” messages.
The message might be in an inbox, just not in the one that you expected. Please see the Why do good messages move to the wrong inbox when trained in Apple Mail? section.
It’s possible that moving a message can make it disappear from Apple Mail due to a bug in macOS 10.15 and later that affects a small percentage of users. You can avoid the bug by making sure that your inbox and spam mailbox are stored in the same server account. The easiest way to do this is to follow the Setting the Junk Mailbox in Apple Mail instructions.
It’s possible that moving a message can make it disappear from Apple Mail if Mail’s database is damaged. The message file is usually still visible on your Mac and on the server. To make the message re-appear in Mail, please see the How can I rebuild Apple Mail’s database? section.
Messages can “bounce back” to the spam mailbox due to being refiltered by another computer (#2), having a disabled account (#3), a server error, or a damaged Mail database (#5).