I just unsubscribed from the list of someone I am a customer of. It is quite likely I will also unsubscribe from their membership soon as well.
They thoughfully provided a feedback form on the unsubscription page.
I gave them the following feedback
I am your customer, not your email punchbag!
It wasn’t just because they sent multiple emails regarding a particular product
I was receiving multiple copies of the same email, from the multiple lists of theirs I had joined for various promotions over the last 18 months.
When you end up with 5 emails promoting the same thing over a 1 week period, fair enough.
When you receive 30 or more over the same period, it just gets a bit much, especially when some of the mailing lists were specifically joined as an affiliate for their products, and not as a customer.