How can I get rid of a spam email?

I have a bizarre issue relating to email. At least it's bizarre to me because I can't figure out what is going on.

For many months I've been seeing email in my spam folder that look similar. Each time, I right click on the email and select "block the domain name" thinking I will not see that email again. Then the next day, I see what looks like the same email but with a word or two different in the subject line.

I set up the email spam filtering in the email application, Outlook or Live Mail, where you type in words that you want filtered out as spam. I entered the words I kept seeing in the subject line like viagra, viagro, cialis, ciolis, etc. But the next day, there it was in my spam folder again.

The second weird thing is, I looked at the list of "blocked domain names" and wrote down a few of them. Then I went to the whois.net website and typed a few of the domain names in there to see who owned them. These domain names came up as being available to buy. So if the spammer doesn't own the domain names, how can my email filter have blocked them?

So how can I get rid of these spam emails? Is there an email application that I can buy that will filter these spam emails even if the spammer is doing some kind of faking the domain names?

Also, I opened one of these spam emails without clicking anywhere and it just had a paragraph of nonsense words. So, I'm wondering why someone would be sending me emails that don't appear to be soliciting any products??

Any comments would be appreciated. Thanks in advance. Kerry