So basically using the mailing list instead of the follow mechanism, that would inform you about those projects if you indeed made the choice to follow them.
There is conflicting information in the faq about those lists.
In one section it is implied as such a promotion tool and devs are told they can only send one per day. In the other section it is said, the mail has to be specific to the transaction. It can't be both true!
If you have a page for sale, you can send an email to all your buyers via itch.io. Do so via the Interact tab, in the email section. You can include the buyer’s purchase URL at the bottom of any email you send to make sure they can easily access any files you may have updated.
Every email has an easy access unsubscribe link, avoid spamming your fans or you might lose access to them.
I see a contradition with that other statement in the other part of the faq.
The email address that itch.io provides, along with the email tool, are made available if you need to contact buyers with news related specifically to their transaction.