How do you use email via these websites? Or do you send and receive email via a VPS or a third-party service?
Third-party, and on purpose. A canister can’t speak SMTP, only HTTPS outcalls, and running my own mail server just to get decent deliverability is exactly the kind of upkeep I was trying to escape.
Sending: the canister calls a transactional e-mail API (I use Resend) through an HTTPS outcall. Two details matter. Outcalls are replicated by default, so every node fires the same request: send a deterministic idempotency key (derived from the order or event ID) so the provider delivers one e-mail and not thirteen. And add a transform function that strips the response down to what all replicas agree on, or consensus fails. The API key lives in the canister, settable only by an admin method and never returned by any query. Do SPF, DKIM and DMARC on your domain once and you’re done.
Receiving: most sites don’t need it. Contact forms post straight to the canister, which then notifies me by e-mail. If you do need an inbox, let a provider receive it (inbound webhooks or an e-mail routing worker) and have it POST the message to an update method on your canister. Still nothing to host.
Alternatives: if you already run a business system with mail (I do, an Odoo instance with its own relay), the canister can call that over HTTPS too, and a tiny gateway in front of SMTP works the same way. But for transactional e-mail from a canister, a managed API is the least to maintain, and at small volume the free tier costs nothing.