the roundcube app from the play store, I've tried uninstalling and reinstalling and still same error, I might just use the stock android mail app but the roundcube one was good while it worked. I use roundcube on my desktop but it was handy to see emails while on the go. If I can't rely on it and have to spend a whole afternoon looking for a solution to get it working then I might just forget about it. I've never been able to do much at all with mail on my phone. I run a business from home and it would be handy to do emails when out but if it's still this complicated to get everything working on mobiles in 2016 then I will just have to forget about it for a few more years. Having enough problems with Win10 at the moment, that's keeping me busy enough
