There was a thread some time ago but I don't think that thread is still active now, how much xrb do you got though? Is it less than 100? It's always safe to trade on exchange sites compared to this forum or to other sites where there's no third party involve. Currently bitgrail, I think that's the safest site to trade xrb and currently has the biggest volume, they've changed their minimum deposit to 10 xrb, I have already tried it so I can confirm that it's really working. If you're a new user on the site when you request a new deposit address then you are already good to go, just deposit atleast 10 xrb to the address then you can already start trading but if you're an older user then you need to generate a new deposit address for the changes to work. It may appear on the deposit page that they require 100 xrb or your xrb will be lost, just ignore that warning message, it seems like the devs haven't changed that yet. If you're still having doubts then here's their official tweet regarding that matter https://twitter.com/BitGrail/status/943619149095464960.