Before Microsoft renamed its webmail service Outlook.com, its familiar domain was hotmail.com.
Hotmail began as an independent webmail service, founded by Sabeer Bhatia and Jack Smith and launched commercially on July 4, 1996. Microsoft acquired it in December 1997 and incorporated it into the MSN family, producing the name MSN Hotmail. The service was later branded Windows Live Hotmail in 2007 before Microsoft introduced Outlook.com in 2012 and completed the transition in 2013.
The rebranding changed the service’s public identity, but existing users were allowed to keep their @hotmail.com addresses. Microsoft also supports or has supported related domains such as @live.com and @msn.com, which is why those choices can look plausible. They were associated with Microsoft’s broader account ecosystem, not the original name most directly connected to Hotmail.
Outlook.com is the modern service name, while Outlook is also the name of Microsoft’s separate desktop and mobile email software.