Cambridge University, one of the pioneering centres of computer science research (since 1937), is retiring its in-house Hermes e-mail system in favour of moving completely to Microsoft Exchange Online <https://www.theregister.com/2020/08/04/cambridge_uni_decommissioning_hermes_email/>. Admin David McBride argues that Microsoft “does not implement IETF standards – at least not competently". In particular, he said: "Its IMAP service implementation is sufficiently poor as to lose data in practice, its mail handling has been seen to violate RFC MUST assertions that causes cryptographic email signatures to be rendered invalid, and it has even sometimes generated outbound email that contains invalid MIME data." He added: "Email services that do not competently support IETF standards, such as SMTP, IMAP, MIME and the like, present significant interoperability challenges and will risk leaving us locked in to using a single vendor." According to the info here <https://fanf2.user.srcf.net/photos.html> (linked from a reader comment), Hermes is not some kind of homebrew proprietary system; it is built on well-known open-source components such as Exim and Cyrus.