usually, cpanel accounts have several tools for managing identified spam, ranging from spamassassin to deleting to requiring further id. Another cpanel-friendly tool is msguarddog.com, which has a free service that has impressive performance (I use it myself).

thanks for your reply. yes, our cpanel has a means of auto - marking emails as spam and places them into the spam folder. But I'm unable to Unsubscribe from the spam folder. So I get all spam emails downloaded anyway.

I think you're solving this in the wrong place. For example, if you could actually unsubscribe in Thundebird, the messages would never be deleted. I suggest you explore deleting at the server, which cpanel can generally do, or create a filter in TB to retrieve from spam folder and delete. For me, mxguarddog solved my spam completely.

thank you. no, the problem is not getting rid of spam. the server blocks it reasonably well. the problem is I'm using Imap folders and I should be able to tell thunderbird that I don't want to subscribe to the spam folder. Thunderbird forces me to subscribe, I can't change it. Several other email clients I use manage this with no problem.