It didn't die because it broke.
It died because it worked.
There was a public Mailo once, and people liked it. That turned out to be the problem. Running the Gmail API at any real scale meant an annual third-party security audit that ran anywhere from a few hundred to a few thousand dollars a year, the toll Google charges to keep a restricted scope like gmail.insert pointed at strangers. For a free little mail-to-self utility, the math never closed. So the original shut its doors.
This is v2, rebuilt for one person and maybe a few friends. Kept deliberately tiny, it stays under Google's threshold for small apps and skips the audit, which is precisely why it can't be handed out to everyone. That is the honest tradeoff: stay small and personal, or go verified and expensive. I picked small.
If an invite found its way to you, welcome to the inbox. If not, the idea is the same as it ever was: mail yourself the good stuff, and keep it yours.
Colin Dismuke