I've a conceptual doubt, I don't know if it's even possible.
Assume I log on a Windows equipment with an account (let's call it AccountA from UserA). However, this account has access to the mail account (Outlook) of the UserA and another fictional user (UserX, without any password, you logg in thanks to Windows authentication), shared by UserA, UserB and UserC.
Can I send a mail from User A using the account of User X via Python? If so, how shall I do the log in?
Thanks in advance
A interesting feature with Windows Authentication is that is uses the well known Kerberos protocol under the hood. In a private environment, that means if a server trusts the Active Directory domain, you can pass the authentication of a client machine to that server provided the service is Kerberized, even if the server is a Linux or Unix box and is not a domain member.
It is mainly used for Web servers in corporate environment, but could be used for any kerberized service. Postfix for example is know to accept this kind of authentication.

If you want to access an external mail server, you will have to store the credential in plain text on the client machine, which is bad. An acceptable way would be to use a file only readable by the current user (live protection) in an encrypted folder (at rest protection).
Send mail via Python logging in with Windows Authentication