How to access attachment content

I am writing an add-in which sends journal items as they created to a
specific user as a mail attachment, like this :

Outlook.MailItem MI = thisJournalItem.Forward();
MI.Recipients.Add("xyz");
MI.ReadReceiptRequested = false;
MI.Send();
....

When the forwarded item arrives to the inbox of the "xyz" user, this add-in
identifies the newly arrived mail and tries to access the attched journal
item :

Outlook.MailItem MI = Item as Outlook.MailItem;
Outlook.Attachments atts = MI.Attachments;
if (atts.Count == 1)
{
Outlook.Attachment att = atts[1];
....

At this point I am stucked because I could not find a way (a method or
property) to access the attached JournalItem. I could save it to a temp file,
but what after ?
On the other hand, in outlook I can see the attached item as a journal item,
so it must be there somewhere. How can I access it ?

Tanks,
Laszlo