You'll get this mission at the same time you get Rannoch: Geth Fighters.  If you haven't advanced the plot to this point, you won't have this mission.  This happens after you've assaulted the Geth Dreadnought.  

Note that it is important to play the Admiral Koris mission, and the other side mission on Rannoch (Geth Fighters) before completing Priority: Rannoch, as it's possible that the outcome of Priority: Rannoch will be influenced by whether or not you've completed these two missions.  Completing either of these two missions will unlock access to Priority: Rannoch.

How do I receive the Rannoch: Admiral Koris mission?
Mozilla Thunderbird 2.0: I have set Thunderbird never to delete a message that is on disk...Thus, after four short years, I have a 4GB Inbox file. Thunderbird needs about 10 minutes to read it, and even then I can't compact it. Anyone have some suggestions?
