rule to move email to folder according to alias ?

not quite really.

With other email providers, in the header remains something like this:
X-Original-To: skynet@someserver.biz
Delivered-To: skynet@someserver.biz

I just made a test, sending from a provider-A, an email with 2 BCC: one on provider-B, one on Office365

The email received on provider-B and on Office-365 was the same, but the header was different.
Opening that one arrived at Office365, those fields were missing:
X-Original-To: skynet@someserver.biz
Delivered-To: skynet@someserver.biz

They were instead present opening the email received ad provider-B

Off course, as you said, in the email header received at provider-B, it was still missing the email address used for BCC to office365.

It looks like that office365 removes/hide the header fields (X-Original-To and Delivered-To)

My question remains partially open:
if somebody send me an email in BCC to an alias of mine, (for esemple alias1@myserver.com) how can I automatically move it to a given folder? for example ealias1

thank you