To block a Sender in Outlook Express
To add an email address to the list of blocked senders in Outlook Express:

Highlight a message from the person you want to block.
Select Message | Block Sender... from the menu.
Click Yes to have all existing messages from the blocked sender deleted from the current folder.
Future messages are blocked even if you answer No to the question and keep existing messages.
Windows Mail or Outlook Express automatically adds the sender's address to the list of blocked senders.

Blocking is Not For (Against) Junk Mail
Send spammers can pick a new, different email address for every junk email they send, blocking by sender address is not effective against this annoying type of email.

Blocking Entire Domains in Outlook Express:
In addition to individual senders, you can also block whole domains in Outlook Express. And of course it is possible to remove a sender (or domain) from the list of blocked senders.

Block Messages from a Domain in Outlook Express
To add a domain to the list of blocked senders in Outlook express:

Select Tools | Message Rules | Blocked Senders List... from the menu in Outlook Express.
Click Add....
Type the domain you want to block.
Finally, click OK.


Outlook Express does not have a built-in spam filter.

You have a couple of options:

Switch email clients. Mozilla Thunderbird is a free, open source email client that does almost everything that Outlook Express does (the main exception is Hotmail support) but adds additional features such as a spam filter.

Buy a filter program, such as Cloudmark Desktop that works with Outlook and Outlook Express.

For more info. with screen shots go to "Outlook Express Tutorial - Filters, how to stop spam" http://www.webterrace.com/outlook/filter.htm