Default retenční nastavení Message Tracking logů v Exchange (řešeno na v2010, ale podle mě to stejné je i výš) je 30 dní – dost málo.

Změna se provede přes Exchange Management Shell tímto cmd:

Set-TransportServer <Identity> -MessageTrackingLogMaxAge <Age>

(age value, enter it as a time span, as follows: dd.hh:mm:ss where d = days, h = hours, m = minutes, and s = seconds. The valid input range for this parameter is 00:00:00 to 24855.03:14:07. Setting the value of the MessageTrackingLogMaxAge parameter to 00:00:00 prevents the automatic removal of message tracking log of files because of their age)

see