# DNS for self-hosting OpenMail

Replace `example.com` with your domain and `<VPS_IP>` with the server's address.
OpenMail leans on Mox's `dkim`/`spf`/`dmarc`/`dane`/`mtasts` packages, but the
DNS records below are operational and must be published by you.

## Inbound (receive) — required for milestone 2

```
; route mail for the domain to this server
example.com.        MX   10 mail.example.com.
mail.example.com.   A    <VPS_IP>
mail.example.com.   AAAA <VPS_IPv6>        ; if available

; reverse DNS (PTR) — set at your VPS provider, must resolve mail.example.com
<VPS_IP>  ->  mail.example.com
```

## Outbound (send) — deliverability, milestone 3/5

```
; SPF — authorize this server to send for the domain
example.com.   TXT   "v=spf1 ip4:<VPS_IP> -all"

; DKIM — publish the public key for the selector OpenMail signs with
<selector>._domainkey.example.com.   TXT   "v=DKIM1; k=rsa; p=<BASE64_PUBLIC_KEY>"

; DMARC — start at quarantine, tighten to reject after monitoring
_dmarc.example.com.   TXT   "v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com; adkim=s; aspf=s"
```

## Secure transport — recommended (Mox supports both)

```
; MTA-STS — publish policy + serve https://mta-sts.example.com/.well-known/mta-sts.txt
_mta-sts.example.com.   TXT   "v=STSv1; id=20260621000000"
mta-sts.example.com.    A     <VPS_IP>

; DANE/TLSA — pin the TLS cert for port 25 (requires DNSSEC on the zone)
_25._tcp.mail.example.com.   TLSA   3 1 1 <SHA256_OF_CERT_SPKI>
```

## Notes

- Many cloud providers block outbound port 25 by default — confirm your VPS allows
  it (or request an unblock) before milestone 2/5.
- DANE/TLSA requires DNSSEC on the zone; skip it if your DNS host lacks DNSSEC and
  rely on MTA-STS instead.
- Warm a new sending IP gradually; reputation is the real deliverability cost.