If a spam conversation has found its way into your inbox, you can easily move it to your Spam folder.
In the conversation toolbar, click the Spam icon:
The conversation will move out of your inbox and into your Spam folder. Once it's in the Spam folder, the conversation will no longer appear in results when you search your mailboxes.
Once a conversation is in your Spam folder, you can use the conversation toolbar to do several things with it:
If you need to locate an email that has been marked as Spam, you can do that from the Spam folder in the sidebar: