I'll offer to everyone what I do to help lose some of that spam, if you use Outlook Express.
DISCLAIMER: These instructions below will set your Outlook up to delete messages without you ever needing to see them. Remember the golden rule of programmers. Garbage in, Garbage out. You have to realize that the computer only acts to your inputs. You should always check your deleted file before you close outlook, to ENSURE that these rules didn't delete an email you wanted, especially in the first weeks or so of using rules. You could be missing email you wanted. Its not an exact science, but if you are vigilant, you will learn to properly filter out your spam from real email.
First off, you need to set your outlook express to wipe your deleted items directory everytime you exit. (you don't have to, but i find its easier and saves you from manually doing it later... especially, like me, you can get upwards of 20 spam mails a day)
Blocking email addys is good, and if you do that, keep doing it, the rules are used to ensure someone who sends the same stuff over and over with different emails gets stopped. You can do both a rule and block address on any email.
In outlook express, click on Tools in the top toolbar. It will show a list below it. Click on Options. This will open a new window with all your options. In the top index titles, click on Maintenance. The first line on that index should be "Empty messages from my 'Deleted Items' list on exit". Ensure this box is checked, then click on the 'OK' button at the bottom. Now everytime you close Outlook express, it automatically deletes everything in that folder.
K, to the next part. Actually setting up outlook express to filter out spam. What we will do, is make 'rules' for your email. So say for example, you open outlook express and you get some porn spam, that has the word 'hardcore' in the title. Hopefully, none of your friends send you the word hardcore in the title. That is why its important to pick words you feel will never be sent in email you want.
1) Click on once and Hi-lite the offending msg. (don't double click it and open it) Now go to the top toolbar and click on 'Message'. This will bring up a list below it. About halfway down that list, click on 'Create Rule From Message'. This will open up a new window that allows you to pick and choose conditions and actions for your unwanted email.
I find the easiest way to filter email is to pick certain words in the subject line that would not usually come from friends or wanted email, but show up in spam. (hardcore, penis, credit card, qualityoffers, dbdirect, optinbyrequest, etc.etc.etc.) Once you get used to using the rule maker, you'll find its easier to pick certain words, either in the subject line or even in the message body to ensure you don't see the spam. If your ISP is spam tagging your email, by putting the word spam in the subject line, like someone said above, it makes it easier. You can just create a message rule that says to delete any email with the word spam in it.
So continuing on...
2) Pick your conditions. You can have multiple conditions per rule, but lets keep it simple. Ensure that 'Where the Subject line contains specific words' is checked and nothing else.
3) Pick your actions. I usually just use 'Delete it' but you have multiple options including not downloading it from the server and deleting it from the server. So click on 'Delete it' for now.
4) Completing the Rule. In the box underneath your actions, it shows the rule. But you're not done yet, you have to tell the rule what word you want to use to key off the rule. So click on the blue link, which will open a new window. In the space provided, type in hardcore. (or whatever word you want to use for that rule) click on 'OK' which will close that window.
5) Read over your complete rule in the 'Rule Desciption' box provided. It should basically read:
Apply this rule after the message arrives
Where the Subject line contains "hardcore"
6) Click on 'OK' wait a second, and a window should come up stating the new rule was sucessfully added. Close that window. Your new rule is added. These rules only work as the mail comes in, so you will notice that the offending message to begin with, is still in your inbox. Just delete it like normal.
7) You're done! Now, from now on, any email with the word hardcore in the subject line will not go to your inbox, but to your deleted items folder. And if you turned on 'clean deleted items folder upon exit', if will be deleted automatically as you close outlook express.
I hope these rules were somewhat easy. I wrote it for first timers - once you learn how to do it, it will get easier. Just realize that one rule won't cover all. I have about 40 rules. It covers subject lines, parts of email addys (example: if you get alot of email from different people from the same server email@example.com, firstname.lastname@example.org, etc. you can make a rule that says if the words hardcoreemail.net shows in any from line, delete it) and parts of message bodies too.
It covers alot of the spam now. Once in a while a spam mail gets through the cracks, and you can deal with that as the time comes.
Please read the disclaimer again, and ensure that especially in the first weeks, ALWAYS scan the list in the deleted folders section... you want to make sure you aren't deleting wanted email by accident.
Hope it helps, its alot to read, but very simple to do once you get the hang of it. Happy spam hunting!