Ohhh. This is about this link and the fact that having a gazillion purchases with a bundle ... is a gazillion devs that could send one of those mails.
https://itch.io/docs/creators/interact
Yeah, preemtivly opting out of such lists or requiring to opt in, might be an idea. I can unfollow, but I can not unpurchase. Or block those mails in settings.
Is there reasons to even have this mechanism (still) available? Sounds to me, like this became obsolete with introduction of devlogs and the general following mechanism wich people would use, if they want to hear from that dev and that is a definite opt in and controllabe before the fact in settings and not after the fact by opting out of what might look like some spam mail. From the description those mails were intended for update notifications (to make sure they can easily access any files you may have updated)