Don’t open spam. Many pieces of spam contain HTML code which will open a connection to a Web server operated by the spammers. When you connect, you have verified that you opened the message. That informs the spammers that they have a good e-mail address, which — you guessed it — results in them sending you even more spam. Delete spam without opening it. Therefore, don’t use your e-mail program’s preview pane. Previewing spam is the same as viewing it.
Therefore, leave your spam messages untouched. Just delete it.