I have to disagree with those convinced he has to be on dating sites to get the spam.
Sure, it could be. However, in my career I worked at an anti-spam email company for awhile.
One of the things I had to do was to set up what was called a honeypot. It was a server setup with email addresses. All we had to do was click on a link on even nonsexual websites. Practically anything selling something.
And we'd use the email address to send and receive email--not even to any odd addresses at all.
Within minutes, shoot, even seconds, the email would come pouring in. Spam of all stripe.
Dating sites, porn, politics, selling toasters, wanting political discussion. Everything!
Once your IP address is being squirted out onto the internet via email, someone is grabbing that information and using it.
It's enough to make you both be impressed with antivirus software vendors and want to light your laptop on fire and go offline.