There is this nice tool that will allow you to send a template to a list of users:
Custom emails gmail from list
There is a more basic version here, that does not allow to add personalized variables inside the mail or even in the subject http://www.labnol.org/software/mail-merge-with-gmail/13289/
There is another tool also from LabNol, that will allow you to track with Google Analytics that the mail has been opened or not:
A bit of an offtopic for this blog. I just wanted to write about the reading habits.
Most of the traffic that visit HolaRails are coming on Wednesdays. Yes, that is the peak day for visitors. What does that mean? traffic is not evenly distributed among the days of the week. As you would expect it is lower during the weekends since people are not working. but during the weekdays I would expect it more even. It is not. Monday and Friday are significantly lower than the rest of the week. It all looks again, like a “normal” distribution. Funny.