I've been doing some email marketing myself so watching starbucks email me time after time is quite interesting. They've been really wanting my business, with so many good deals one after another that I suspect regular starbucks patrons are not getting. Also noticing the choice of email titles, content etc.
What I would really be interested to know is what is going on behind the scenes. These are definitely data driven customised emails. I could be wrong and they're just sending to everyone, but I doubt so as there's no reason to do that, they would just be losing money.
What I suspect is going on is the system detects that I havn't bought any starbucks for a long time. So they started following up. And following that, they have been tracking my open and click rates, deciding that this guy is actually still interested in Starbucks given how he has been opening all the mails and reading them.
All these automated of course. The wonders of big data and technology.