The same happened to my old "...@hotmail.com" email, Microsoft deleted old childhood emails, still bitter about that. Per https://answers.microsoft.com/en-us/outlook_com/forum/oemail... , the limit is 365 days of inactivity.
When Outlook.com was first made available as a mail domain back in 2012, I immediately went and registered a few accounts, figuring that it would become a high-profile service pretty quickly. One of them I have almost never used, and in its eight-year lifespan it's received...(checks)...7 emails. All of which were from Microsoft. That account is still up, though, and I don't believe I've checked it from the website i…
Startup idea: SaaS that you register you email addresses and periodically does an IMAP request to keep them active. Premium tier would provide actual archiving of your emails.