For the technologically challenged, what is a sequential file, what is its significance, and how does one clean it up? Most email programs don't actually delete a message: they just move it to another folder.
All you have to do is empty your Trash folder, or the Deleted Items folder, or whatever your email client calls it.
It's easier just to go to www.mail2web.com. You can delete the Spam there without it ever going into your Inbox in the first place. Try it. I use it all the time.