I'm using an RPI with the latest HG release as of 14th September 2015. I've tried installing Mono to deal with possible SSL issues on Gmail but as of yet still no success. I've tried all possible ports, I've dropped the @gmail.com on the username option and SSL=TRUE but still no success.
Does anyone have a working Gmail alert on a Raspberry Pi in HG and if so could you possibly post exactly what you did to achieve this, including settings and any other adjustments you had to make to achieve this. I've spent so much time on this with very little success. I do have another Debian based program running on the RPI, MotionPie, a video based security system which sends email alerts so I know that this function works on the RPI.