Blackberry users should exercise caution with email as noted in this warning:

QUOTE: Have a BlackBerry? Watch out for a new malware campaign that masquerades as a legitimate account activation mail, Websense researchers warned. The latest malware is spreading and infecting networks using fake emails that inform recipients their BlackBerry ID has been created, researchers from Websense ThreatSeeker Network said. The text of the email is the same as the legitimate BlackBerry account creation notices sent by Research in Motion to new users. It’s the attachment that is dangerous. Users are encouraged to download the malicious file and run the attachment. Attackers are then able to drop other malicious files and modify the system Registry, making it automatically run malware programs whenever the system starts.