@Dustcan  
That’s set in the future time line. Luster Dawn doesn’t exist in the present.

@Background Pony #9139
 
Didn’t account for that. So 8125 is an upper limit. So for a lower limit (going to exclude sound cards because there’s no sense it in and they’d be very expensive), the thickness of a thick card is .3mm, but they’re folded over, so .6, which is 6x thicker than the basic paper. 8125/6=1354 as a lower limit to number of dispatches.

@Dustcan
 
With her mane, I thought maybe she was Sunset’s. I mean the coat works for Sunburst + Starlight, but not the mane. Looking at other ponies, it seems like manes actually kinda work along same gender lines. Pinkie’s sisters have manes like their mom. Fluttershy has a mane like her mom. Twilight Sparkle has a mane like her mom. Bright Mac has a mane like his dad. Flurry has a mane like her mom. Shining has a mane like his dad. Spitfire has a mane like her mom. So it’s pretty likely Sunset Shimmer is her mom, but no clue who the dad is since the color doesn’t fit with it being Sunburst. IDK, it could be Sandbar, judging by where he vs Sunset stand on the color wheel.

I was reading Stellar Flare’s last statement as “Those lamps won’t stick themselves.” I’m fluent in sideways.

@Kalash93  

“If you’re not going to put that tongue to use getting me a daughter in law who will bear my grandchild, then I have a whole sheet of stamps with your name on it!”  
“Very funny mom. Wait… these do have my name on them! And my vital statistics and address!”  
“I’d have included your job title too, but I ran out of room. Now get licking!”
 
 
@Kalash93  

Is it just a letter though? There could be cards in there too, which use slightly thicker material (and which would likely doubled up, since many cards open). We could even assume some extra thickness if you think she’s the type to have gone with the cards that have a soundchip in them to play a greeting. Like maybe “Happy Holidays from Sire’s Hollow!”, or something like that.
 
Still a substantial amount of letters, though.

You know I’m surprised Bobthedalek hasn’t jumped on the “Luster Dawn is Sunburst and Starlight’s child” headcanon yet.

@Neko Majin C
 
It’s a scheme by the maretriarchy to ensure that all stallions have strong tongues.

Has Equestria not yet invented self-adhesive stamp technology?

@Digital Seapony
 
She’s making him lick stamps on marriage proposals to every of age fertile single non lesbian unicorn mare between age of consent and a little bit older than Sunburst’s age in the regional mail directory. It’s also to get him primed for marriage.
 
An envelope is about 3.5 inches tall, the stack of letters is about 9 times taller than the upheld envelope. So that’s 31.5 inches, or 2.6 feet worth of paper. A sheet of paper is .1mm thick. Convert that to inches and you get .00393” thick. Divide 31.5 by .00393 and you get 8015 sheets of paper. That pony really DOES want grandfoals!

C’mon, Stellar, you’re gonna kill the poor colt if you make him lick ALL of those letters.

Christmas cards were no joke before Email became a thing.

Are they sending out Hearth’s Warming Eve cards, or is she making him reply to every letter from Sire’s Hollow he’s ever ignored?

“It’s not gonna lick itself.”

Poor Sunburst

that’s a lot of letters,