Earlier quoted context omitted.
I remember during the Ashley Madison leaks there were so many work emails. I wouldn’t even use work email for buying a movie ticket much less organizing dates and affairs. Some people are weird like that. There’s also old people who only have work emails. Lots of different people in the world.
Arguably if you're having an affair it's something to keep from your private email but your work email may not be as visible to a spouse ...
Although sending it to work is probably the most secure from a spouse.