Ah, too late to fix my mistake now. Just a little slip. :) Thanks for the correction. I know the difference of course, just had the wrong thing in my mind while typing!

>whenever you go to change tabs with the mouse.

Only fire the event once, as most people will be leaving. Not flipping between tabs.

>If somebody is interested in subscribing, then a subscribe box at the bottom or side of the content is fine.

Research and A/B tests say otherwise. I was sharing a popular method - I don't use it myself. I don't agree with it and I don't browse sites that make use of the annoying pop-up modals.

But the trade off of driving away some users to capture many more is one many people and companies would make.