Unsolicited Calendar events appearing from emails

I was looking at my Calendar and noticed an appointment for a server migration. I do not work in IT.

I didn't click on the Calendar link, but went back to my Inbox and searched on the information that I could see in the unopened Calendar summary. Lo and behold, there was an email that I hadn't opened (knowing it was spam, or worse, a phishing scheme) with the same info.

Is this a known "feature?" I certainly don't want unsolicited mails with dates and times ending up on my Calendar. Isn't this a security thing, when anyone can send me an email with a date and time and it gets added to my Calendar without my consent or knowledge? Any advice appreciated.