IIRC Microsoft's internal email still ran on Xenix at the time (until Exchange betas got good enough for internal use c. 1995?), so perhaps more trademarks than some sort of absolute hatred of Unix. Also note that one of the two APIs that NT OS/2 was initially going to support was POSIX, albeit perhaps more because the US government wanted that than a true love of UNIX. Although the design rationale document (ntdesrtl) does lament that existing POSIX test suites tend to also test "...UNIX
folklore that happens to be permissible under an interpretation of the POSIX spec".
Did Microsoft never run Microsoft Mail internally?
It was an email system that ran on top of file system. If I recall, mail clients connected over a networked drive to access mailboxes. So it was never regarded as being very scalable.
Yes, MS Mail for PC Networks used a shared file system for email.
The Workgroup Apps (WGA) divison ran MS Mail for PC Networks since they produced MS Mail. Gotta dogfood your product. The WGA email system used a Xenix gateway to connect with the rest of Microsoft.
The rest of Microsoft ran MS Mail for Windows with a Xenix email backend and address book, since MS was already using Xenix before MS Mail for PC Networks existed.
Windows for Workgroups 3.11 contained a one postoffice-version of MSMail, (which could be upgraded to the full version).
