If you believe your Email Account has been hacked, or someone stole your password, you will need to immediately contact your Email Service Provider. Let them know your Account has been compromised, and they should be able to assist.
Once you have changed your password for your Email Address update your new password in IncrediMail. In order to do that, simply click the 'Tools' menu, and then 'Email Accounts'.
Choose your Email Account, and then click 'Properties'.
Under the 'Servers' tab, you can update your password.