It seems that my email has been hacked by spammers. There is nothing in my sent folders but it seems that there are spam emails going to everyone I have ever sent email to, not just those in my address book. How can I stop this?
Good intentions are no substitute for a good education.
I take my fun very seriously.
It is not necessarily the case that your account was hacked. You can send out emails using sender information that is not your own. If a spammer has gotten hold of your email address (and that is hardly a secret) he can send emails in your name. There is no need to use your account.
Now, if ALL of your contacts were mailed, then perhaps your account WAS hacked, and your address list stolen. But that means that the damage is done; changing your password will not help to defend against that. Not that changing your password is a bad idea by any means...
Hopefully you do not use the same password on other accounts, such as your online banking if you do that. If they have got the password, they could try access other accounts, based on info in your emails, such as your bank, paypal, share dealing and so forth.
Without being paranoid, you may consider changing all your passwords. There is an easy way to do this. Simply select a short word, such as egg or hen, add a number, such as 6, then change the password to xxxxegg6 where xxxx is the name of the website. So if you bank with I don't know Chemical Bank, when you go to their site and log on, your new password would be chemicalegg6. Paypal would be paypalegg6. That way, you have an original, unique, strong, unguessable password for every site without having to remember the passwords.