ourbigbook.comwas leased from: porkbun.com/. Unfortunatly, HTTPS on Heroku with a custom domain requires using a paying tier, so we upgraded from the free tier to the cheapest paid tier, "Hobby Project", to start with: stackoverflow.com/questions/52185560/heroku-set-ssl-certificates-on-free-plan
On the Porkbun web UI, we added a DNS record of type :whereand we removed all other
ALIAS ourbigbook.com <heroku-id>.herokudns.com
heroku-idwas obtained from:
heroku domains:add ourbigbook.com heroku domains
CNAMErecords from Porkbun.
Next, we setup forwarding from
firstname.lastname@example.org Ciro Santilli's personal gmail accont. This is done in part because it appears that we are required to provide a from address for OurBigBook Web email sending with Sendgrid, and that email has to be verified. Having Porkbun host it costs 2$/month, and we are trying to use as much free stuff as possible until there are actual users on the website.
Note that if you try to test from your own personal account, the redirect automatically skips sending as it notices that it would redirect to the sender. To test it you have to use some secondary email account instead.