Retain 3.x, 4.x
I am trying to have Retain archive from a journal mailbox, but only messages sent directly to the mailbox are being archived.
Journal messages are special and are not archvied unless "Enable Journaling" is enabled in the Retain job configuration under the Journaling tab.
NOTE: It is a recomended best practice not to use a journal mailbox as it can negatively impact the performance of your Exchange system. See "How to transition from journaling to rolling in-place hold for Exchange archiving".