Spam email has been around since 1978 so it's not a really recent thing as spam email has been around as of now 41 years.
It's believed that spam email got it's name spam from the canned meat spam which is undesirable to some people including myself.
Some people love the spam meat however some people like me find the spam meat bad tasting and unwanted to eat.
So some people do believe that spam email got it's name from the spam meat that is easy to fix and store but spam is not good to all people.