The sign-up confirmation email is sent by firstname.lastname@example.org. This email address remains the same if you change your URL or are using a custom domain alias.
I hope this helps. Let me know if you need any further clarifications.
Hi Patrick , thanks for your question! Yes, you can have emails sent from your company domain. We'll configure that for your account. Send a request to email@example.com and let us know the email address you would like it to send from. Thanks!