If you are having trouble because your mailbox is full, you need to go to the actions menu and select "Purge deleted items". This is because when you delete a message or mark it as spam, the system doesn't actually delete it. It moves it to the folders called "deleted items" or "junk e-mail". You need to "purge" to free up space in your mailbox.
Also, if your mailbox is full, I can't respond to you via email to your hsiung.net account! If you're confused about purging, send me an email from a different account and I'll respond.
-Bob