Usually just clicking on SPAM when you receive the message will direct it to your SPAM FOLDER and any subsequent emails from this person will go there...if that doesn't work try below....NOTE:If you want to edit the settings of SPAMGUARD click on SPAM in the folder section on the left side of your email page. Once in you will see SPAMGUARD and the edit option.
If you are using yahoo classic OR the new versionGo to "Options" It is above your email Click on "Mail Options"
Click on SPAM
Enter the address you want to block
Click on “Add Block”. Go above and click on SAVE CHANGES
On occasion the sender changes their name BEFORE @ so block that DOMAIN the following way...
If you are receiving several emails from the same domain, but various ID's, the easiest way to stop them is to enter the domain into your "Blocked Addresses".
In Yahoo! mail, to block the senders domain (hotmail.com):
◘ Click on "Options, upper right corner of mail page".
◘ Then "Mail Options".
◘ Click on "Spam" from the list on the left.
◘ In the "Add a blocked address" box, enter the domain (only the part of the email address AFTER @, do not include @). Note: I have recently seen where you should have the @ included...try them both.
◘ Click the "Add" button.
Now, any email from that domain, no matter what ID is used to send it, will be blocked.
FINALLY...do not forget to click on SAVE CHANGES at the top of the page......
NOTE: there is a limit of 500 addresses in the Block Address box. There may come a time where you have to go in to this box and delete some.