Hello and thanks for reading!
I have a section in the Contact layout with these fields:

Opt out of Email
Do Not Call
Do Not Contact

I've added a checkbox called Lead Only/No Auto Emails. As users manually add new Contacts, they'll be checking that to prevent them from receiving automated communication.
The idea is to set up a new flow. When a contact makes a donation for the first time, automatically uncheck that box.

We are using SFDC's BCC Email-To-Salesforce feature, often creating new contacts with it. Is it possible to know that a contact originated from one of those emails and automatically check the box?

The problem with defaulting it as checked is that there are a lot of integrations creating new contacts in this setup: donations, text messages, Facebook ads/leads, web forms, etc. I would need to update all of them to explicitly UNcheck that box.