is there red flame icon showing in the mail list to signify the mail is considered spam by Thunderbird?

In IMAP mail account mail has two ways to get into the designated spam/Junk folder either Thunderird will put it there and give it a junk flag that shows are the red flame, or the mail server puts it there and in those cases the mail does not have the spam flag set and the spam column shows a pale grey outline of the spam flame instead of red.

In the case of server designated spam, Thunderbird never sees that as being in the inbox, so inbox filters also never see the message to do anything with it.

Thanks for your answer! I did not recognize the colours of the flag. The reason is that I am handicapped in view and work in "Black and White". But I had the ideabvefore that maybe the server could put it into the Spam folder. But - nevertheless - I suppose the filter can work in the inbox _and_ in the Spam folder. Is there no way to manage this? And: Reading the Spam folder I activate the filter manually. But I must activate twice. Why? The messages disappear for a moment and come in again. Why?

re : But - nevertheless - I suppose the filter can work in the inbox _and_ in the Spam folder. Is there no way to manage this? Sorry, but no. Filters only work automatically on the Inbox.

But it sounds like the email really is spam especially as you want to delete it. Does the server auto empty the Spam every X days ? Some servers auto empty every 30 days. If yes, then does it matter if it sits in Spam for a while ?

Ideas: In Thunderbird, in 'Account Settings' > 'Junk Settings' for the account you can choose to auto delete email older than X days, so gaining some control over how frequently spam emails get deleted. This means you get a bit of time to check them in case some good emails go into wrong folder, but it also clears it down so does not keep them for long.

If server is putting the email in 'Spam' folder then perhaps you could logon to webmail account and see if you can create a filter to put emails from that email address directly into the server Trash folder, so bypassing the Spam folder.

RE: that sounds tricky and is a real option. I understand that I have to solve the problem on the server side before the messages are loaded and treated Thunderbird and its filters. There is a server option to delete after 30 days. My problem is that sometimes I did need this time to control. On the other side I like to clean the folders as fast as possible to hold overview and not to forget as answers... But I must think about