Is it ok to view a person's profile individually and send an one-time thank you note? If that is ok, why can't that be automated? Since the intent and purpose and outcome is the same. Just that a computer executes that human intent.
The receiver hasn't given you the ok to e-mail them, and sending mass unsolicited e-mail is basically the definition of spam. If you want a special way to contact users, have them clearly opt-in to it. Could be an e-mail list, could be a github issue that you ask them to subscribe to, ...