I can probably find it, but do you know what the name of the Sidekiq job was that triggered the email?
If you are not able to access the site because you aren’t receiving the activation email, you can create an admin user and password with rake admin:create. Full instructions are here: Create an admin account from the console. That should allow you to login to the site.
It sounds like you’ll still need to sort out what’s going on with email delivery though.