I just signed up with my Github account, but the signup form filled in my secondary email (which happened to be no longer accurate). However, I couldn’t change it anymore, so first created my account and then changed it in this Discourse forum account settings afterwards instead.
PS I don’t need help with this - I entered the forum, just reporting
PS2 Originally posted here: Signup via Github doesn't use primary email - Site Feedback - Let's Encrypt Community Support