These features are planned. We may even see the mailbox as early as season 1. I just wanted to say that I don't think I can implement these features without charging crystals per transaction. Why? If these transactions were free, then it would essentially make my game completely free without limits as long as you have multiple email addresses. The bank is the only thing that really encourages people to play on one account (aside from the convenience of not logging in and out constantly). If they make multiple accounts to bypass it and then trade the items for free then there's literally no reason to ever pay for anything.

As you might imagine, a feature like this could potentially make a lot of money. If that was the case it could even reduce the cost of other features.

good idea hope its not a huge amount per mailing but totally understand the crystal cost.

Not sure yet... thinking single digits. Maybe 5 cents. I think to mail an item it would have to charge the mailer (just like IRL). The auction house would charge the buyer, but the seller would receive the gold, though the AH would take a cut.

At least that's my current thinking.

Like the idea, seems nice and the cost is fine.
One thing though: can you make also the receiver able to pay for the mailing cost - after a confirmation ofc?
If I want an item from someone else and he agrees to mail it to me, I should pay for the shipping. Also happens like this irl ...

I think a better option than arbitrarily monetizing features that are generally free on almost any game would be to introduce paid and unpaid features that incentivize playing on a singular account. Some examples of unpaid features could be for every difficulty you defeat, or maybe even just for defeating Hell, you get an account-wide Experience/Magic Find boost, making leveling alts and gear farming easier. Perhaps introduce unlockable titles if you've defeated Hell Nalatos on a certain amount of classes like Dauntless at 2, Fearless at 5, et cetera. You could also eventually introduce and Achievement-like system that is either just an E-peen measuring stick or maybe even has some rewards attached to it based on certain benchmarks. Tons of fun little account-wide things can be done for free to make people want to stick to one account.

For paid features you could add in perks per character slot unlocked. I'd have to give these more thought to come up with ideas for that though. I also assume you plan on rolling out new content, Expansion style. That's definitely an area you can justifiably charge for, and I doubt that anyone who is too stingy or broke to pay a few bucks to snap up some character slots is going to be willing to pay for an expansion on two separate accounts.

I feel like I could come up with easily dozens of ideas in both of these sections if you want to hear more.

Now, if you feel you HAVE to charge for mailing/the auction house, why not make it one lump sum to unlock? Then, even if people want to get around paying for character slots by making multiple accounts they have to now buy, at the very least, the right to utilize the mailing feature on two separate accounts. You could also charge a lump sum up front that allows easier/faster/more convenient usage of the Auction House, such as No Posting limits or Cheaper Postings for your entire account once you buy it. Mailing could cost gold as well and get a similar treatment. Perhaps make both free to use on a limited scale with options to Pay Up to the features being nicer. I think this is a stronger deterrent from making multiple accounts but I could be wrong.

Either way, just my two cents.

Some good ideas. Feel free to continue suggestions as I'm sure this will continue to evolve.

In my opinion, it would be worth considering charging an auction house fee in gold pieces as well, in order to address the need for gp sinks that has been discussed in other threads.

In terms of real world tax system design, taxes are ideally broad based so they do not distort economic activity, hard to avoid but relatively straightforward to pay.

Nevergrind already has a gp death penalty, which could be viewed -- in the right light -- as a progressive income tax.

An auction house tax could be viewed as a consumption tax, since it could be expected that every player would interact with the AH at some point.

The advantage of having a small number of sinks with wide effect is that it would be relatively easy to tweak them up and down as the state of the economy required. In contrast, having lots of fiddly sinks or prices set in code would make it difficult to make adjustments.

Anyway, just something that occurred to me.

Makes sense. It would be easy to adjust something like an auction house cut.