Table of Contents
Email and SMTP
Transactional email for folk.zone services: registration confirmations, password resets, opted-in notifications. Getting it wrong means broken signups and spam-folder delivery.
Provider
All services send through Resend over SMTP:
Host: smtp.resend.com Port: 587 (STARTTLS) Username: resend Password: <API key>
The API key is shared through the RESEND_API_KEY environment variable in the server Compose file and the environment ~/.env on casa. Free tier is 3,000 emails/month, 100/day.
DNS Records
The folk.zone domain is verified in Resend. DNS lives at Porkbun; the required records are:
| Type | Host | Value |
|---|---|---|
| TXT | resend._domainkey | DKIM public key, copied from the Resend domain dashboard |
| MX | send | feedback-smtp.us-east-1.amazonses.com, priority 10 |
| TXT | send | v=spf1 include:amazonses.com ~all |
The MX and TXT records on send coexist with the existing send.folk.zone A record for the file-sharing service. If the domain ever shows “failed” status in Resend, trigger re-verification with POST /domains/{id}/verify against the API.
Recommended addition: DMARC as a TXT record on _dmarc: v=DMARC1; p=quarantine; rua=mailto:dmarc@folk.zone; pct=100.
Per-Service Configuration
| Service | Mechanism | Sender |
|---|---|---|
| WriteFreely (write) | WRITEFREELY_SMTP_* env vars | configured in WriteFreely config |
| Rallly (meet) | SMTP_* env vars | noreply@folk.zone |
| Kutt (go) | MAIL_* env vars | noreply@folk.zone |
| DokuWiki (wiki) | smtp plugin + local.php | noreply@folk.zone |
| Mastodon | SMTP_* env vars | notifications@folk.zone |
| Forgejo (git) | FORGEJOmailer* env vars | git@folk.zone |
The DokuWiki container has no MTA, so it needs the plugin. Its config keys are plugin.smtp.auth_user and auth_pass, not smtp_user/smtp_pass. Use smtp_ssl = tls for port 587.
HedgeDoc runs anonymous-only and does not send mail. IT-Tools, CyberChef, Send, ArchiveBox, and EtherCalc have no account system and send nothing.
Registration Spikes
Open or semi-open registration can exhaust a 100/day free tier in an hour. Mitigations:
- Enable the app's email queue where it exists (Mastodon and WriteFreely both support rate-limiting outbound mail)
- Stagger invite sends; do not issue 500 invites at once
- Monitor the provider dashboard and alert near the daily limit
Why Not Self-Hosted SMTP
Deliverability from a residential IP is the blocker: PTR records depend on the ISP, and residential ranges are flagged by default. The fix is routing outbound SMTP through a cheap VPS as a smart relay, which reintroduces a monthly cost for marginal gain. Not worth it until paid ESP tiers become the constraint.