How to Historical Delete on Meeting-responses

We have setup archiving in the following way:

Historical Archive (which runs daily for 24 hours duration time)

Historical Delete (which runs daily and deletes data older than 2 days)

This gives us a 2 day extra buffer of the Exchange 2007 "Journal" Mailbox

Everything workds as expected except one thing:

Journal Messages which hold a Meeting response (like: Accepted/Denied/..) aren't deleted and 'skipped by filter' if i see the detailed job log.

I didn't set any filters and all types/folders are included in the activity.

Anyone seen this before?