I don't think I'd put anything in it. I sort of expect all those thousands of cooperative like-minded strangers to have a better sense of their current situation than I do, and not to read emails that serve no communication purpose and that they know the contents of already.
I'm writing this with "the tired energy of a long flight" rather than fervent munchkinry, but hey, someone's gotta point out the null hypothesis.
I do write notes to myself to remind myself of what I need to do the next day. These are sometimes quite cryptic when I read them them. I was certain that "nec-funu-wat" would make perfect sense the following day but I still haven't deciphered it. I also write notes to myself about _amazing_ ideas. These frequently, although not always, cause me to smack my forehead the next morning.
What would I email myself instead of mostly practical notes? Questions to ask that stranger, my future self. Are you avoiding something that's causing emotional distress, but you need to do anyways? Did you eat/sleep/exercise/rest enough? Are you balanced emotionally? Are you getting what you need out of life today? How did your life philosophy affect what you did today? Did you make time to chat with folks? Do you need a hug? Did you pet the dog? Madu nannda wubba? Tueree!!
Well, I guess I sort of do this, although not with email and only for certain very narrow purposes: I use a few tools (calendars, emails to myself that describe an action item in the subject, a notes app that displays on my phone's home screen) to make sure I don't forget things I want to do something with later. This is basically just part of my personalization of the Getting Things Done method, although what I do these days doesn't look much like GTD as described in the books, but it's carried out in the same spirit: make a decision about what to do now, and then either do it now, put it in a system you trust so you are sure to do it later, or drop it.
Certainly an email to myself every day could achieve the same thing since I could edit it every day to contain the current state of the information I want to store in these systems, although I imagine more could be done with such a generalized mechanism that I can't do with my narrow way of using the tools I currently do.
Several days ago, I wrote an email to myself.
That email will now be sent to me every day.
All it is is a single draft in my Gmail drafts folder, with the Mail Conductor extension sending it out at 10:00 am. I can modify the draft whenever I want, each time improving it.
Consider, with the fervent munchkinry of a final exam... What would you send yourselves?
(Helpful anchor point: What would you share with a guaranteed audience of thousands of cooperative strangers who thought very much - but not quite totally - like you?)