MailKit, Office 365 and OAUTH2: Problem in authentication of a server side app

[Clippy]

MailKit, Office 365 and OAUTH2: Problem in authentication of a server side app

[Clippy]

Late response, but I hope this saves someone else the week I spent researching this.

The simplest/best answer is to use Microsoft.Graph. See this:
[https://learn.microsoft.com/en-us/graph/api/user-sendmail?view=graph-rest-1.0&tabs=csharp](https://learn.microsoft.com/en-us/graph/api/user-sendmail?view=graph-rest-1.0&tabs=csharp)