When attempting to create a Mailbox Audit report (Sent or Received) and clicking on the eclipse [...] button next to the 'Mailbox DN' field the mailbox against which the report is needed is not listed.
This is due to either of the following:
1. Tracking Log or Default Gathering has not been run against the server hosting that specific mailbox
2. Use ADSIEdit to find out what is the exact value of the legacyExchangeDN item. Often customers expect to see the mailbox DN based on the Display Name but the legacyExchangeDN may be something different affecting in this way the order in which it is found in the list. E.g. a mailbox with Display Name 'Marketing Desk' may have legacyExchangeDN as something completely different e.g. 'DeskMkting' and therefore be alphabetically listed with DNs starting with 'D' rather than 'M'