Life before the internet...I just googled chain letters and the wikipedia article says they are essentially pyramid schemes. Using a pyramid scheme for social good, rather than fraudulent profiteering, was actually one of the starting points for this idea. It's nice to see it come around full circle. Thanks for the feedback!
I also really like the "offline" approach to this idea. I think it can be really important to look for low tech as well as high tech solutions, especially when dealing with a population that isn't always engaged with the internet.
I really like the idea of adding a coupon or offers to the pack. I think, as well as giving the receivers of the pack more of a reason to read through it, it also gives the senders more of a reason to have a pack sent to a friend because they know their friend will get additional benefits from it.
Sponsorship is also a great idea. I think it would be really important in the funding and publicity of the packs. I've talked a bit more about sponsorship in my above response to Kate but I agree sponsorship would definitely be a good thing to focus on to ensure the packs are a success.
I hadn't initially considered sponsorship but it's a great idea. It would be great to get a mixture of private and more socially minded sponsors involved. Private sponsors who might want to promote a particular brand amongst the older population, United Healthcare for example, and more socially minded sponsors such as the NHS or AgeUK who might aim to increase engagement with their services. I suppose the nice thing about the idea is that it could be sponsored wholly by an organisation or it could be run in campaigns with each campaign being supported by a new sponsor. Sponsors would bring the advantages of financial support as well as increased publicity.
To bring in Bettina's thoughts from below, sponsors might also want do to more than just have their logo on a pack. They could also be persuaded to offer extras, such as a 50% off at a favourite restaurant or coupons for shopping at a large supermarket. This would increase engagement with the sponsor but would also act as an incentive both to the sender, to send a pack to a friend knowing that they will receive a tangible benefit, and to the receiver, who would be encouraged to look through the pack.
Thanks for the feedback! Let me know if you have any other ideas.