About two weeks ago, the volume of spam on my outlook.com account significantly decreased. There was nothing wrong with it but it turned out that many of the e-mail (also important) doesn’t go to my inbox nor the junk folder. They just disappear. 

I know that because I use mail redirection from external account and I can see that e-mails there. Not all messages disappear, it's about 8 of 10. Lost e-mails weren't marked as spam on external account.

What about that?