email attachments

I often receive emails with attachments from pc users & forward them to other pc users.
The problem is that the forwarded message often has dropped the attachment.
I'm using Leopard, a .mac mail account & charter cable.
Any suggestions?

Thanks

Note moved to a better forum (OS X - Applications and Games):

do you use the web interface at .mac or do you use a email client (Mail, Entourage, et alia)?