1. Add a domain under a status page's Email sender section
On the Scale plan, open a status page's settings and add a domain you control, for example yourcompany.com or status.yourcompany.com, plus the part before the @ (status@yourcompany.com by default). Sending domains are shared by every status page on the account; which one (if any) a page sends from is a separate per-page choice on the same screen.
2. Publish the DNS records
You'll get a DKIM TXT record, an SPF TXT record plus an MX record on a return-path subdomain, and a DMARC TXT record at _dmarc.yourdomain.com (or your organizational domain, if you're sending from a subdomain and already publish one there). All four are shown as both the relative name your DNS provider may want and the fully qualified one, since providers disagree about which to type.
3. Verify, and expect the DMARC record specifically
We re-check automatically (every minute while pending, every six hours once verified) or you can click Verify now. A domain is only marked verified once BOTH the DKIM/SPF records pass our provider's check AND our own DMARC lookup finds a policy: DKIM-signed mail from a domain with no DMARC record is exactly the setup that lands in spam, so we require it even though the provider does not.
4. Select it on a page, and understand the honest fallback
Once verified, pick the domain (and optionally a display name like "Acme Status") on any status page. The decision is made fresh every time an email actually sends: if the domain later becomes unverified, a record disappears, or delivery is paused, that email goes out from RealUptime's own identity instead, and an audit row and dashboard notice say so. Subscriber mail never queues or fails silently waiting on your DNS.
5. A domain can pause itself on bad delivery
If a domain crosses a small bounce or complaint threshold in a rolling day, it pauses automatically to protect your (and our shared) sending reputation, and subscriber email falls back to RealUptime until you resume it from the dashboard after fixing the list or the DNS. The counts that caused the pause stay visible so you can tell whether it's safe to resume.
Go deeper
The full reference lives in the docs: Status pages documentation. Error codes named above are each explained in the error-code reference.