Over the last several months my "blocked senders" list has grown exponentially. Can anyone tell me if it is possible to block a domain using message rules. I've been getting spam from several domains that change the first part of the address on every spam. Each time I get one I go into messages and block sender. Then, next day freud@mpogp.com becomes zyzzx@mpogp.com and I have to add to the blocked list. I want to block mpogp.com and have done with it.

You should be able to create a rule blocking a domain. I use Eudora and you can do it with that program.

What program are you using for an e-mail client? I also use Eudora, and there is a filter setting that allows you to send all files from a domain to a separate file, which you can review and discard.

I use Outlook Express.  

Given your encouragement I found the answer. On Outlook Express page I went to TOOLS/MESSAGE RULES/BLOCKED SENDERS LIST and selected the offending email address. By clicking on MODIFY I was able to delete the address part of the domain. Now all spam from that domain is automatically deleted.