Do they have the option to send SMS with codes before login?
They do. But they implemented 2FA poorly on android for me and I lost 0.04BTC. They didn't reply me either.
They just need to key log your computer if you don't have 2FA, they can easily use your mnemorics to transfer the money. I would have preferred it more if it's 2 of 3 as there is a faster way of recovering Bitcoins if they close down one day. Currently, the nlocktime requires a certain period of time.
GreenAddress supports supports 2of3 as well as 2of2 and 4 different kinds of 2FA: SMS, Google Authenticator, automated phone call and email (with PGP support). We encourage users to set more than one as well as recovery emails just in case they lose access to a device or their email provider disappears.
We only require 2FA when you spend or when you change important settings informations - requiring it to login would be overkill given that with the mnemonics alone you can already find out on the blockchain which transactions belong to a wallet.
ranochigo, what problem did you have on 2FA on Android? Can you describe what you found poor about it? we are sorry if your last support email wasn't replied to, please send an email to
info@greenaddress.it and we'll be happy to help.
