Hotmail was FreeBSD on the front end until it switched to Windows IIS in an ISAPI filter. The back end was Sun E4500 with T3 purple storage. Then they switched

Hotmail was FreeBSD on the front end until it switched to Windows IIS in an ISAPI filter. The back end was Sun E4500 with T3 purple storage. Then they switched to HP with some terrible RAID crap. Messenger was borne from the Net Meeting team in an informal weekend hackathon (before that was a thing). Backend stored the buddy lists and was 3 Hotmail ustores (Sun E4500 with EMC clariion storage). Front ends started out as Sun 420R then switched to Windows bit by bit (DP, SB, and then CS and PS). The Messenger HTTP gateway always ran in IIS.