For the GMail aspect, you'd need to use IFTTT along with something like CoRE.
I have my Blooms and Lightstrips go yellow when I receive an email stating I have a package ready for pickup at UPS using the GMail IFTTT channel.
I have a virtual switch setup that gets turned on when a new GMail message meeting that criteria comes in.
I then have it set up in CoRE so that when that switch comes on, it will turn my lights to the specific color. I have multiple ones of these (for new text, missed calls, new FedEx package, etc).
CoRE can also flash the lights, so it will do what you need.