You don't know what happened afterwards. Perhaps your provider threw
it away silently. Perhaps the bounce message itself got lost.
I see you are @outlook.com. This is an... idiosyncratic provider: they
invent strange rules "to protect you" (in reality rather to protect
their business model). Perhaps they bounce the bounce message (Microsoft
is like that) and then you'll never know your mail got lost.
As things stand I trust the Debian mail admins more than the Outlook
ones to play by the rules [1]. Much, much more.
Cheers
[1] one basic rule of mail is that, when you've accepted one you
are responsible for it.