Ask HN: How to make a profitable business from a newsletter app?

Hi, My name is Bryan and Happy Holiday to all hacker news readers.

situation: I created a project that helps instagram users to rediscover their old photos buried down deep in their timeline. It’s a service that randomly draws a photo that the user taken 6 months on instagram and sends it to them via email on a weekly basis. (like the flashback feature, that everpix just to have)

questions: 1. what is a likely business model you would use in a pdt like this that only engage with the users once a week via email.

Initially, I was thinking of adding ads into the email that I sent. However, I later realised that it is not possible todo that. adsense programme does not permit adsense ad code to be placed in email messages

some plans in mind: - Advertiser-Supported Email Newsletter - still go for ads, but I would go and find sponsors. Like the sponsored post on iosWeekly or JavaWeekly

- Or I try to add features to the emailer. For example. I will add flickr integration and this is a paid service. (but I also understand from many HN reading, that to be a paid service I must really be solving a pain point. (which I think I am, but I’m not sure thou)

- Or I would go for open source. Maybe be using gittip service. If there is donation, great. Otherwise I would just let it run, since I using the service myself.

What do you think? How would you create a business model around such a product. Love to hear your feedbacks.

p/s this is actually my first post on HN and to avoid fellow readers to think that I’m creating an Ask HN question to spam my project url. I did not put project link in the question itself. But if you any of you are interested to find out more so that you can help advise me. The service is here (http://bit.ly/marcusapp)