I think this could be done without being too obnoxious: 'We try not to send emails to people who're not interested - click here to confirm that you still want to get this newsletter'.

It doesn't have to be every month - each time someone reconfirms their interest, you could wait longer before asking again.

You don't need to send this email to everyone. Only to those users who haven't clicked on a single link of your regular newsletter for the past X months.

And doesn’t have any negative repercussions forcing people to constantly repeat themselves. “Yes, I still want what I said I wanted a month ago.”

“Why did you stop sending it to me?”

“You didn’t say you it.”

Yes I did! 15 times!

Well, not this month.

It’s like consent for sex is supposedly supposed to be like today for some inexplicable reason.