custom Outlook 2003 sorting and Encrypted emails

Hello,
I m developing a plugin to seperate encrypted and unencrypted emails in
outlook 2003. Outlook 2003 presents a grouping interface to the user so the
user can group the emails. By default outlook groups these emails according
to date i.e Tuesday, Yesterday, two days ago , Older and etc. The user can
change this group sorting to the fields available in the group sorting
dialog. The question is; is it possible to custom sort the emails in the
folder. Ideally i want there to be two groups Encrypted and Decrypted and so
i could place the emails in these groups. ? someone at outlookcode.com
suggested me to look for some property and so i could sort the emails
according to that property. Untill to defrenciate the encrypted email from
unencrypted email i m accessing the headers of the email to read the content
type of the mail. Is there any other property available that lists that its
an encrypted email. Summing up all

1- Is there any property so i could know its an encrypted email. or how do i
guess its an encrypted email
2- Is it possible to have two custom groups Encrypted and UnEncrypted. ?

Thanks
Danish.