Custom Domain
How to add your custom domain to a mailbox
Follow the steps that the app shows you (from mailbox settings)
Send Emails
Make sure your SPF TXT DNS record allows EmailThing to send emails on your behalf:
v=spf1 include:_spf.mx.emailthing.app -all
Receive Emails
TODO
Receive Emails (advanced)
TODO but its the Cloudflare Email Worker method