I'm trying to set a custom Message-ID, but it's always sent with something like this:
Message-ID: <BLU0-SMTP18947C4078EE3208EEF12E5AC710@phx.gbl>
I'm using all the same mailing code and headers to send from gmail. With gmail my Message-ID is being set correctly.
Any idea what's going on here? Does outlook.com not let me use a custom Message-ID header?
