spam can be prevented. First of all Yahoo has spam protection. You can choose what is spam and what is yours. You can control it at the server. If you want to use Outlook Express with it there is an extra fee.

Hotmail you can also control spam at the server. Click on mail, then options and choose only people in my address book. Soon they will be charging you an extra fee for this service(they way they are moving)

What I would do is have an account for my online accounts, such as yahoo.com and an account for my personal messages like gmail.com. Only the people you know would recieve and send them there. If you are using it to send jokes, I would also have an email account for this, because there is a high persentage of people that forward jokes, instead of making their own, meaning that your email address has traveled along with the forwarded email, allowing someone else to get your email address to add to their spam list.

Hope this helps.