Dear Discord,
It is so nice to get a letter, even one from you! Between you, Luna, and I, (I'm having Luna be my honorary scribe for today) I've been kind of lonely with out the normal letters from Twilight. I am so proud of her for finishing her studies, but I still miss the little filly I taught for so long. Sorry, I was getting a bit nostalgic there for a moment. Remember Discord, this stays between Luna, you, and I, got it? I just don't want my little ponies to think I'm needy or something. I'm sorry to hear your visit is boring, but as you said, it's better than Canterlot, don't tell anypony this either, but I couldn't agree more, but I know if I moved to Ponyville, even just had a vacation home there all the other Canterlot ponies would surely follow me, you however, I bet nopony would follow you.
All the best,
Princess Celestia
PS
Dear Discord,
Sorry if this is hard for you to read, it is 3am on my internal clock, she had to use me as her 'honorary scribe' on the one day I sleep a week, anyway, my mind is foggy, but I have a small prank you could play, it would annoy the heck out of who ever you chose to play it on, I will send it in a separate letter on one condition, you won't use it on me, got to go Tia is getting suspicious.
Luna
PPS
She really is lonely so if you could consider sending her more letters.
I dunno if you noticed, but in chapter two, in Luna's part (the PS) you spelled clock wrong. Please fix it.
3855888 oh my goodness! I am so sorry! I fixed it! OMG.
3856193 Pfft.

That made me laugh.