Is the Spam folder subscribed? For an IMAP account, right-click the account in the Folder Pane, Subscribe, Refresh, and check the Spam folder. A Junk folder is created by TB's junk controls, and is separate from the provider's spam controls and folder.

Thanks for the quick answer. It is subscribed to a folder " ....@imap.comcast.net/Junk". The problem is that Junk does not exist on Comcast's email site. The folder is called Spam. I am asking if I can change the link in Thunderbird to "..../Spam". I tried but I cannot edit the setting.

Maybe you have to enable the Spam folder for IMAP acess through the Comcast webmail settings, and then it can be subscribed in TB? I don't think it's possible to edit folders that are defined by Comcast.

You are right. I cannot edit in Thunderbird nor on Comast's website. Thanks for trying.

David, just to clarify (and forgive me if you are expert and don't need this. sfhowes is certainly expert!) Junk and Spam are entirely different, not similar names for the same folder. Spam belongs to Comcast and you can't change it, but you can choose to see it or not see it in Thunderbird (subscribe). Thunderbird downloads it like any other folder from Comcast if you are "subscribed". sfhowes is working with you on that part. Junk belongs to Thunderbird, and is where it keeps messages you mark as junk, as sfhowes said earlier, so Thunderbird can learn what you consider to be unwanted, and is where messages Thunderbird detects as spam are placed after they are downloaded. So there may be no need for Comcast to see Junk anyway. If you access Comcast online first, those messages will be in Comcast's other folders somewhere. Just check the Thunderbird Junk sometimes in case it incorrectly marked something that is actually Not Junk. Regarding the location of Junk - Account settings may help. https://support.mozilla.org/en-US/kb/configuration-options-accounts#w_junk-settings-panel See the lower part of the settings screen - destination and retention - to set where you want Thunderbird's Junk to be placed. I believe you can make it appear in Comcast if you want, but as Junk is only processed and populated in Thunderbird after downloading from Comcast, and should contain unwanted messages anyway, I would not. Hope that helps!

Thank you to both you and sfhowes. It is working properly, now. I think that by clicking the Repair Folder button (in the Properties link for that folder) I connected the Comcast and Thunderbird folders. I can now see the "Spam/Trash/Junk" emails without having to go directly to Xfinity.com.