In order to get an attachment from a quarantined message without releasing it, do the following:
1) Find the quarantined mime file by:
a) Open the message up in the QMS, by clicking on the subject
b) Click on the properties tab
c) Under Core | Container Path, you'll see the path to the mime file. It should look something like: 2015/12/11/11/1b6m4pv.1b6m4q3.msg
d) Get a copy of that .msg file. The container path starts in ...gwava/services/qms/data/storage.
2) Change the file extension from .msg to .eml.
3) Open it with Outlook or Groupwise client and download the attachment from there.