Description of problem:

opened attachments are temporarily saved to /tmp readable for all
users when using default permissions

Version-Release number of selected component (if applicable):


How reproducible:
always

Steps to Reproduce:
1. open attachment in mail news
2.
3.
  
Actual results:
any user can read the attachment

Expected results:

when an attachment is opened a directory is created under /tmp which
only the user can enter, this is used to store attachments until the
end of the mail news session.

or

a tmp location under home is used like ~ .tmp/


Additional info:

even using a different umask the file name is often descriptive enough.