Why don't you just block him in your mail reader.

Outlook Express > Tools > Message Rules > New > From People > Delete it > Type in the email address

He won't know that you are not seeing the message and may grow tired of sending them in time.

using mail2web to access my pop mail.

using mail2web to access my pop mail.

If you don't know how to block it in "mail2web" you will have to wait for a response from someone who is familiar with it. I'm not.

im not trying to block them, im trying to report them to yahoo for spamming.

Forward the message (with full headers) to abuse@yahoo.com

he could just start all over again using a different address - a hotmail one, or something. but he will probably be even more disgruntled then.

another solution would be to automatically bounce back every email that he sends you, so it will look to him as if it has been undelivered.
he will soon stop it then. because not only will he think you're not getting it, he will also have to start deleting his own undelivered emails.
the free 'mailwasher' program can do that for you.

Have you checked that the mails really are from Yahoo? With the limits that Yahoo and Hotmail place of volume mailings it is far more likely to have the address spoofed.

Check the headers against a service such as spamcop.