That sounds like you're using IMAP.

Is it subscribed? Right-click the account, select Subscribe, re-select the account if necessary and look to see if the Spam folder's checkbox is ticked.

Thank you! It's simple when you know how!

The "Chosen Solution" may work for some, but not for me. I am not using IMAP. When I right-click on an account name, nothing happens. I have tons of spam on my mobile device, some of which is NOT spam, but I never see those emails on my desktop Thunderbird. Help, please.

This thread is about using IMAP. Since you are using POP it does not apply to you. You should Google POP vs IMAP to learn the differences. The short version is POP is only aware of the Inbox on the providers server so you will never see a Spam folder.

Well, I use pop3 on both my desktop and my android phone and my tablet. Both phone and tablet (using Blue Mail app) show spam folders, with lots of emails in them. Many of those emails are NOT spam, and I'd like to see them in my inbox on the mobile devices, and make sure I see them somewhere in Thunderbird on my desktop. I've checked both Outlook.com, and Gmail.com, and the servers aren't (seemingly) marking anything as spam, so I'm just trying to figure it out. I thought, if there is a "spam" folder for Outlook, and I could see it, that might help.

I seriously doubt you have the account set to pop on your phone and tablet. If you see a Spam folder on either device it is not set for POP. Either way, start your own thread because this one is solved and does not apply to you.

Both my outlook and my gmail accounts are set to pop3 on my android devices. Your doubt is unfounded. This thread was NOT about imap - the op said nothing about imap, only the first responder said "imap". However, it is clear that I should go elsewhere, if only to avoid your expertise.

[Personal attack removed by moderator. Please read Mozilla Support rules and guidelines, thanks.]

Hi Poalima, Zenos' post was marked as the solution by the person who asked the original question (Judykap). Your issue may have similar symptoms, but it is likely a different cause/solution. You should use https://support.mozilla.org/en-US/questions/new where volunteers can get more details about your setup.

Because this thread is solved and more people might start using it for their own questions, I'm going to lock it.