It’s the new questline in Patch 7.3.5., and it appeared to be just wonderful!
The questline itself is very easy. First, you need to find a randomly spawned lost letter by one of the mailboxes in Dalaran or buy one in Auction House. I wanted to do this asap, so I paid 60k and got the quest.
The quest sends you to Black Market boss in Underbelly, and you witness how a dwarf recieves his armor. Then you get a mail which wants you to the postmaster’s office. It was tricky to find, but for those who have difficulties, there: you need to follow the lane to petmaster, and you will discover a postmaster tube by the cemetery. Click it, and you’re in the office.
Like all other shops in Dalaran, the office is just gorgeous. So many details that I’ll be touring there for at least half an hour! Anyways, your questline continues,and you need to visit Feralas and Eastern Kingdoms to deliver stuff (it’s very funny), then you get access to the minigame.
The minigame offers you 6 continent tubes.
A name of the place with a name of a continent zone pops up, and you click the corresponding tube to send the letter. You need to be real quick with it. The first achievement is sending 30 letters in 60 seconds, so you have just 2 seconds per letter. The second achievement is sending the same 30 letters in 60 seconds, but addresses are not full! So you will have to quickly define which town is in which continent.
It’s just the achievement for me: difficulty is at the level, but not ridiculous, and it requires knowldge of Azeroth geography :) And you get a mailbox toy and a pet as a reward.
I have not yet tried the second achievement, but I’l be doing it with eager.
Lorewise, the questline is important to see how your mail is sorted and sent out. It appears that they send it to certain towns and villages, but don’t bother about the receiver’s name :)
Well done, Blizzard. I strongly advise everyone to do this questline, even if it means spending 60k :) Totally worth it.
Gnomecore 
I’m not all that interested in the pet, but I think I’ll probably do the questline eventually just to be able to poke around in the mailroom and to play the letter-sorting minigame. I wonder if the letter-sorting game will still be re-playable after you’ve gotten the second achievement for it?
LikeLiked by 1 person
I think it may be!
LikeLiked by 1 person
And, when done, you get a copy of that starter letter to give to a friend? I think that is what I’m hoping, if true, that it will be passed around the guild.
What does the mailbox toy look like?
And, finally, grats; it sounds like fun.
LikeLiked by 1 person
I’m not done yet with the second achievement, can’t tell :)
LikeLiked by 1 person