restricting sending attachments through Yahoo, Gmail for some users through squid 2.5 on FC3

[Ankush Grover]

hey friends,

 I am using squid 2.5 on FC3.  Accessing Yahoo mails, Gmail mails or
any other web based mail systems are allowed in my domain  and I don't
want to stop the access to these webmails but certainly wants to
restrict the some users from sending any attachments through these
webmails.

 My company wants to restrict some users from sending any attachments
through these webmails. Is it possible to have such kind of
restriction for some users?

Please let me know if you need any further inputs.

Thanks & Regards