Opening email attachment on archived email causes logon box.

We are using AM 5.4 and when our users have an email in archive manager that has another email as an attachment it will prompt for login before it will allow that email to be forwarded or the attachment to be opened.  It will work if the user has administrator or mail admin rights.  But we don't want to give all of our users this right because it would give them the ability to search everyones email.  Is there a way to get this to work without giving them admin rights?