The ToS explicitly prohibits using or sharing buyers Personal Information with third-parties.
The "Interact - Send Email" tool is an itch.io functionality, thus it's part of your agreement and it's explicitly warned about on itch.io ToS and Privacy Policy, to which every user agreed to.
If the Seller is using Third Party services to send emails, then you can report them.
Devs who join a bundle to collect buyer's contact info are following an officially recommended practice to grow their audience.
I understand this is annoying. But itch.io gives tools to batch unsubscribe to game emails. Here's the complete guide:

