Microsoft exchange runs SMTP and web. It needs a minimum of two names to function, and can require several others depending on features. Microsoft just released

Microsoft exchange runs SMTP and web. It needs a minimum of two names to function, and can require several others depending on features. Microsoft just released a vulnerability fix that actually requires you add a new unique name to your certificate. That sort of annoyance often leads people to use wildcards. And prior to let's encrypt, a wildcard is often cheaper than a cert with six names like I've been dealing with. So in that situation, there are a lot of SMTP wildcards on a web server in the wild.