very serious problem with the reply address for outlook.com accounts using an alias address. when the email is sent, the from address looks correct. when it’s received, it looks correct until the recipient does a reply and then the address to which they’re replying has changed to “firstname.lastname@example.org” where the xxxxx is a strange series of 15 letters and numbers. actually sending it will eventually bounce back.
Maybe this is the answer, although maybe not what you would like.