Authorization to access Outlook

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When I invoke Outlook on my laptop I am prompted for a username and password for a specified server ("dub402-m.hotmail.com" which is meaningless to me). The username box is pre-loaded with my MS account/Outlook username and the password box is empty. (There is also a box to check if I want the system to "save this password in [my] password list": I leave this unchecked). If I enter my Outlook password my Outlook inbox is displayed. If I don't supply a password but press the Cancel button sufficiently persistently I also gain access to my inbox but a triangle containing a black exclamation mark on a yellow ground appears in the Outlook icon on the taskbar. When I perform these same operation on my desktop machine there are no such authorization formalities, it goes straight to a display of my inbox. I infer that in the case on my desktop, there is some connection between my user account and my MS account such that a user logged in as me on this machine is not required to provide further authorization information in order to gain access to my Outlook account. If someone can explain this difference in behaviour and direct me to a source of authoritative information about the link which appears to exist between user accounts on the one hand and MS accounts on the other I would be grateful.