Good. You opened this message. This isn't actually asari military command. They're busy tending to what's left of their planet.
So you survived our fight on Thessia. You're not as weak as I thought. But never forget that your best wasn't good enough to stop me. Now an entire planet is dying because you lacked the strength to win. The legend of Shepard needs to be re-written. I hope I'm there for the last chapter. It ends with your death.
-KL
It's been ages since I played it. I honestly don't remember what flavor of teamrocket-style defeat the guy eats before sending that message.