Are you trying to send a security update to someone who can't download it by sending them an e-mail?
If so, remember, many e-mail service providers limit the size of your attachments. If sending from a Windows machine, attachments may be difficult to be read by Mac users.
Are you trying to receive the official security update for a 10.4.11 or 10.6 via e-mail from someone else?
Be careful, someone may be trying to spoof Apple's official update with one of their trojan own trojan horses. If at all possible, you should download security updates from the official source at a place with Macs, and copy to a USB Flash drive if needed to shuffle to a place with limited internet access.
Security updates whose file name are similar to that, and may be the same as that, can be found on this page:
Additional ones that are newer can be found here:
P.S. Your tags make no sense for the computer in your profile, or the computer whose forum this thread was posted in. No Powerbook can run 10.6. If you were desiring to discuss about a different machine, or a different operating system I can ask a moderator move this thread to a more appropriate forum.