Hotmail account in Apple Mail on MacBook Air

Well, I give up. I'll really tap into the collective knowledge to try and get help with this odd behavior: I have two MacBook systems, one a Pro, Intel (2019) and the other, an Air, M4 (2025) both on macOS Tahoe 26.1. Both work quite fine, EXCEPT for a Microsoft (yes, that) small nuisance: my old and trusted hotmail account works perfectly well in Apple Mail on the Pro and on the Air, but simply does NOT send mail on the Air. Everything else works fine and other mail accounts work in and out with no issues. As far as I can tell, the configurations of my hotmail account are the same. on both machines It seems to be somewhat related to authentication but I simply don't know where else to look for differences/parameters.

I know this should probably be taken to Microsoft but they would turn me down as this is a "free" service so I hoped some kind soul in these communities might feel empowered by the Spirit of Christmas and help me out.

Thanks in advance!

-Fernando