Can you offer trades here using Global Steam keys outside of your Steam account?

Why would you send them by mail ? You can just post them in the Steam chat

Yes, you can. Some do it that way using Steam chat. But it isn't recommended by Steam to do so. So you do so at your own risk of being scammed. And there is nothing Valve will do to help when not using their trade window. Also, Steamgifts is not liable either.

Ok then, but you're still not using Steam trade, since you're merely posting a product code. Anyway, if that's the case then I might just exchange my items using Steam chat. Thanks for the tip. \m/^_^\m/

I guess I'll rely on user trade feedback in Steamgifts before making the exchange. Thanks!

Yes, but you would need to do it via the trade forums at www.steamgifts.com/trades, then you would be in the right plce.

Yup, I'll use steamgifts trade forum and steam chat. Thanks a lot. \m/^_^\m/