This isn't so much that I need some advice as me giving you guys some advice, so yay!

If someone gives you a certain name to use to address their card, USE THAT NAME. Don't write their username on the envelope or the postcard unless they have specified that they are fine with that. Don't use another name than what they have provided.

Why? Because it's not the name they want on their mail. They told you what name they wanted, use that. Maybe they don't want other people to see their reddit username. Maybe their username reflects the name they wish to use, whereas the name they provided you with reflects the name it is safe for them to use, and you are putting them in at best an uncomfortable situation, and at worst literal danger by using that name. It's not safe to be out as trans everywhere, please be mindful of this. There are a million good reasons not to want a card to be addressed to your reddit username, and interestingly, they are both valid and not requiring of a justification to you. :) Keep your fellow RAoCers safe!

In another order of idea, if you are doing a form, something I've been regularly seeing, and it means so much to me, is that the form owner asks which name to use while addressing the envelope / postcard, and which name to use to write inside the card. For those of us who need to keep our names hidden, for any reason whatsoever, THIS MEANS SO MUCH, and it's absolutely great to have a space to use this versus having to write something like this in the notes: If you are writing a card that goes inside an envelope, please write Érik. If you are writing a postcard or addressing an envelope, please only use M. Literally cannot count the times I've had to write this. You don't have to implement this, but I feel like it's highly considerate of your fellow RAoCers to add a question to figure this out. It's not difficult for you, but it means a lot in terms of feeling seen and not feeling like you have to spend your entire day explaining it.