Updated Wednesday, 12:46 p.m.
Brain blip: I got an email today from Forbes pointing out that I had credited Fortune with this idea. My apologies, and a correct attribution, to Forbes.

In a short story titled, "The Other," an elderly Jorge Luis Borges writes of meeting his younger self on a bench by the Charles River. The 18-year-old is actually sitting on a bench in Geneva, and barely remembers an old man trying to talk to him.

If you could talk to the person you'll be one, three, ten, twenty years from now, what would you say to your older self?

Fortune's Forbes' E-Mail Time Capsule: "Simply fill out the fields below, decide how long you want the capsule to be sealed for, and hit send. We'll do our best to make sure the message gets delivered."

They've triple-covered their part of keeping the emails. But your email address is the weak link: Will your current provider still be around? (Will you?)

Since they chose Yahoo as one of their backups, a Yahoo address might be a good bet.

It would be a lot cooler to be able to email your younger self ("Don't go out with him! The Red Sox will win the World Series in your lifetime! Buy Google!") but they haven't worked out that one yet.

Deadline is Nov. 30.