Ownership and Permissions on emailed files

[Ian Sights]

Does any OS other than X check the Ownership and Permissions of a file? 
I emailed a file to a printer and they forwarded it to the people 
actually making the pens and I got the message back that the file was 
read only. I resent it, making sure that the Group and Others were set 
to read & write and they still had trouble. I don't think they are on 
X, but since I was getting a passed along message, I don't really know.
What really puzzles me is that the copy that I CC:d to myself changed 
from Read & Write for everybody to read only for everyone but me. Why? 
Did I not change it like I thought? (The original file info still reads 
read & write.) Does it get set to read only for others since I'm the 
user who downloaded it?
Obviously if there's a settings problem I need to figure it out or 
vendors will get really PO'd at me. I ended up resending the file from 
an OS 9 machine after resaving it with Illustrator 8 just to be sure. 
Obviously this is not a good solution long term.

Ideas?

Ian Sights