Spammers are using free web services to make their messages look genuine.
Messagelabs has revealed that some photo hosting websites allows people to upload Flash files and they can be used for animated graphics to direct people to other websites.
Paul Wood, a senior analyst with MessageLabs, explained that the spammer will upload a Flash file then copy the link for that file into a spam message. If the link is followed, the Flash file redirects the victim to a spam site.
As antispam software will scan links in e-mail and block messages with suspicious content, those originating from legitimate websites used for photo hosting will not be blocked.
Wood said: “If you start blocking on domain name only, you can incur a lot of collateral damage.” He also claimed that Messagelabs had seen abuse of Microsoft's Windows Live SkyDrive, an online file service, while Google's Picasa photo service and Yahoo's Flickr apparently escaped spammers' attention by not allowing Flash files.