1. Using my own server. I have my own server where I can create a mail account and collect all mails. Its private and has "unlimited" storage if we speak about text and some photos. Only problem is, I might die before the children reaches the age. The contract for the server ends, all data gets deleted and the child may never get the mail. I would have to write a will and define how to handle the server. Combined with need to chance software, updates and chanced credentials I see the real risk that the documentation does not allow the designated handler to give access to my child. This seems like a worst case scenario. Dying before the child is of age and losing all the stuff I wrote form him/her.
2. Using a freemailer. I could register an account at gmail or similar and collect the data there. The credentials are handled by me and are stored in my will to pass along if I die. If the service goes out of service I can backup and move the data. This solutions sound good, but I feel uncomfortable deciding for my child that this much and highly personal information is stored at someone processing it to make ads.
3. Using a specialized app like timespring. I found one app that offers a service to collect data and give access in the future. https://timespring.com/features/ While I am comfortable paying for such an service it will be 2038 before I plan to give the child access to the system. This is longer that the iPhone is around so it seems unsafe to trust in an App being available 16 years in the future. Additionally it would be much harder for my parents to send data via this app.
Writing and thinking about that matter showed me again how little prepared we seem to be in the context of digital heritage. So if you have any other ideas to organize your digital stuff for the people after you I would be interested. Especially if there is some kind of PW management where I can define some elements that will be send to somebody else If I do not log in after x days.
Best trailmixraisin
I am not a lawyer nor an estate planner but I believe at very least you would want to write the letters in a plain and simple format with date/time stamps and save them to multiple storage devices and also print them out from time to time. Have copies on site and in a bank deposit box. Detail in your will that these letters and USB drives must be given to all your children. There should be a cover page that explains what the letter are as to avoid confusion and to provide context. Plain text paper and text files will not be impacted by any of the numerous future time bugs.
Even better might be to create a living trust and have trust managers that will manually hand a copy of the content to your children in paper form at the same time your assets are distributed to them. The trust manager can have special instructions detailing how they are to reaffirm to the children how important it was to you that they read them. This is of course assuming you do not give them the letters before you pass. Apologies if that seemed a bit morbid.
Paper and ink shows you care. It is also a proven technology.
Good luck.