SAN FRANCISCO, Oct. 26 (UPI) -- Internet security experts warn computer users to prepare for more spam as the holiday season comes up and spammers unleash new methods of attack.

Web services such as America Online, Google and Yahoo will have their hands full trying to block the spam as well, the USA Today reports.

On one day alone in September, America Online blocked 88 percent of e-mails coming onto the system -- that's 3.2 billion spam e-mails.

To counter the email protection found on many computers and services, spammers are using instant messaging to get their ads across.

They use viruses and worms sent hidden in instant messages, which in turn increases the spam on that computer and unknowingly passes it on to others.

Joel Smith, chief technology officer at e-mail security company AppRiver, said spamming is most intense starting in the fall and through the shopping season.