Docs · Deliverability
Deliverability & inbox placement
Deliverability is the reason SuperMailOS exists. Because we run the mail server, the technical work that decides whether your mail reaches the inbox is ours to carry — you get the result without operating any of it.
What we handle for you
- DKIM on every message. Each outgoing message is cryptographically signed with a key whose public half is published in your DNS.
- SPF and DMARC from the server’s zone. Generated for your domain, not templated, and verified live before sending is allowed.
- DMARC reports, parsed. Aggregate reports are collected and turned into a dashboard, so you can see every source sending as your domain instead of reading raw XML.
- New-domain warm-up. Volume ramps automatically as a new domain builds reputation, rather than spiking on day one.
- Sending-IP reputation & reverse DNS. The outbound IPs are monitored for blocklist status and correct PTR records.
- MTA-STS & TLS-RPT. Inbound mail is required to use TLS, with failure reporting, closing off downgrade attacks.
Your side of the deal
A few habits keep the reputation we manage healthy:
- Verify before you send. If you signed up with an external address, confirm it — verified-before-send protects the shared sending reputation, so it’s on by default.
- Send mail people asked for. SuperMailOS is person-to-person business email, not a bulk blaster. Unsolicited bulk sending is the fastest way to wreck placement for everyone, so it isn’t the product for that.
- Keep your lists clean. Repeated bounces and spam complaints are the loudest negative signals a receiver sees. Remove addresses that bounce and honour unsubscribes immediately.
- Be consistent. A stable from-address that people recognise and reply to builds the engagement history receivers reward.
Check where you stand
The free email deliverability checker looks up your SPF, DKIM, DMARC, MX and MTA-STS records and explains any gaps. To go deeper, read why emails land in spam and email warm-up explained.
Common questions
Do I need to set up SPF, DKIM and DMARC myself?
No. SuperMailOS generates them from the mail server's own zone, publishes them (one click on supported DNS providers, copy-paste elsewhere), verifies them live before you can send, and signs DKIM on every message. DMARC aggregate reports are parsed into a dashboard for you.
What is new-domain warm-up?
New sending identities have no reputation, so a sudden burst looks suspicious to receivers. Warm-up ramps volume gradually as your domain establishes a track record. On SuperMailOS this runs automatically from your first message.
Why does my domain have to be verified before I can send?
Sending from a half-configured domain fails authentication and teaches receivers to distrust you. SuperMailOS blocks sending until your records verify, which protects both your reputation and the shared sending infrastructure.
Can SuperMailOS guarantee inbox placement?
No honest provider can guarantee placement — receivers make the final call using signals like engagement and complaint rates. What we do is remove the technical causes of spam foldering and monitor the reputation signals continuously.
Next: secure your account with 2FA or migrate your existing mail.