It's almost considered sacrilegious today to leave work at the end of your workday or (for shame!) on a Friday and simply not check your work email again until you return the office during normal working hours.
Basically, if you log into Pokemon Go through your Google account on an iPhone - which is the first option provided -- it gives "full access" to your account. According to Google's help page, that should only be "granted to applications you fully trust."
Email -- or electronic mail -- can seem old-fashioned when compared to newer social-media and marketing tools. However, when used effectively, it can be an engaging marketing tool with a high ROI or return on investment.