Mailing big items/gold
I have transferred gold to friends/family and never had a problem, they can challenge it if it was just between their own accounts and not something else.
An item like dawn may be a different thing, but if you write up in mail what you will do with it seems to me not to be a problem.
It’s legit to do so and it’s also possible that you’ll get banned. However if you spell it out in email (which I would use. Keep the emails for proof) or chat between the 2 of you what you’re doing then it’s a lot less likely. If either still gets banned, you can contact support and tell them what you were doing, pointing out the conversation, and get it reversed. Might take a couple of days though.
Your guildie can also contact support and tell them he was transferring funds between his 2 accounts and get it reversed.
Some former guildie once transferred 140g or something as a surprise for another guildie to transfer servers. He got banned for it, then he challenged it and got his account back – still he was banned for +/- 10 days?
Guild Website: http://www.wtnf.net
Youtube Channel: https://www.youtube.com/channel/UCb07P-bW94jE3-mKHGToyOg
I loaned a couple hundred gold to a guildie once so he could finish making a Legendary for sale. In return he gave me part of the sale price.
With each transfer of gold that we emailed to each other, we specifically said in the email what we were doing and why. We both kept the emails for a couple of weeks after he sent me my share of the profits. Neither of us had a problem.
It is allowed. Just look at the threads where people complain when the deal goes south.