Defaults.Exposed

How to set up DMARC on IONOS

You want a DMARC record on IONOS, and what that comes down to is one TXT record at the host _dmarc under your domain, holding a short policy string that begins v=DMARC1.

IONOS is the domain’s DNS host and registrar for this record, holding the TXT record that carries the DMARC policy. It does not generate the policy value itself; the reader supplies it and IONOS only stores and answers it in DNS.

The record comes first on this page, with what each part of it means, and the exact IONOS fields it goes into come after, because the record is the same wherever your DNS lives and only the form around it changes.

The record before the console

DMARC is the instruction a receiver reads after it has checked SPF and DKIM on a message claiming to come from your domain. Those two checks each return a pass or a fail. DMARC tells the receiver what you want done with a fail, and where to send a summary of what it saw. The instruction lives in DNS because that’s the one place a receiver anywhere in the world can look up something only the domain’s owner can write.

The host is _dmarc, with the _ character at the front, and the type is TXT. The value to start with is:

v=DMARC1; p=none; rua=mailto:[email protected]

Three tags carry the meaning. v=DMARC1 names the version of the standard and has to come first. p= is the policy: none asks receivers to deliver failing mail as they would have anyway and report on it, quarantine asks them to put failing mail in spam or junk, and reject asks them to refuse it during delivery. rua=mailto: names the mailbox that receives the aggregate reports, which arrive as XML attachments listing which servers sent mail as your domain and whether each one passed.

A message passes DMARC when SPF or DKIM passes and the domain that passed matches the domain in the From header. That matching is called alignment, and it’s why a mail provider’s own SPF record isn’t enough on its own: the check has to succeed for your domain, since that’s the one the reader sees.

Other tags turn up in records elsewhere. sp= sets a separate policy for subdomains and defaults to whatever p= says; the subdomain policy piece covers when it’s worth setting. pct= applies the policy to a share of failing mail. adkim= and aspf= switch alignment from relaxed to strict, and ruf= asks for per-message forensic reports, which most large receivers don’t send. Leave all of these out at the start; the three-tag record above is complete and valid.

Start at p=none. Publish p=reject before you know your SPF and DKIM pass on your own mail and you’ll bounce your own invoices along with the forgeries. The reports are how you find that out, so the rua= address has to be a mailbox somebody opens.

Check that IONOS answers DNS for the domain

The record only works if IONOS answers DNS for the domain, which is true only when the domain’s nameservers point to IONOS. Sign in to IONOS, open Domains & SSL, select the domain, and check the Nameserver settings there. If the nameservers point elsewhere, to another web host, to Cloudflare, or to the email provider, the DMARC record has to go at whichever provider runs DNS instead.

IONOS publishes exactly the TXT record the reader types into the Value field once Save is clicked. It appends the domain to the Host name automatically and quotes the value for DNS itself, but it does not generate, suggest, or check the policy text.

Publish SPF and DKIM before DMARC. The policy tells receivers what to do when those checks fail, so a domain with neither has nothing for DMARC to work from, and a p=reject on such a domain refuses everything that carries its name.

Add the record in the IONOS console

  1. Sign in to IONOS and open Domains & SSL.
  2. Click the domain, then open the DNS section to see the list of DNS records.
  3. Click the Add record button.
  4. Set the Type field to TXT.
  5. In the Host name field, enter exactly _dmarc and nothing else.
  6. In the Value field, enter v=DMARC1; p=none; rua=mailto:[email protected], replacing the address with a mailbox that is read.
  7. Leave the TTL field at its default, since one hour is fine.
  8. Click Save to publish the record.

Set Type to TXT. In the Host name field, type only _dmarc, since IONOS appends the domain itself and typing the domain again duplicates it. In the Value field, paste the plain policy text starting v=DMARC1;, with the mailbox after rua=mailto: replaced by an address that is read. Leave TTL at the default IONOS offers.

Look for an existing TXT record at _dmarc before you add one. A domain gets one DMARC record, and a receiver that finds two treats the domain as having none, so if one is already there you edit it. Paste the value without surrounding quotation marks and without a trailing space or line break, then compare the last few characters against the record above once it’s saved.

Traps in the IONOS form

A record that’s present and malformed is worse than an absent one in a single respect: it looks done. v=DMARC1 missing from the front, p= misspelt or left out, a rua= without mailto: in front of the address, or curly quotes pasted in from a document all produce a record receivers can’t parse and so ignore. The DMARC typos piece lists the ones that show up most often in the census.

With those checked and the record saved, run the free scan below. It looks up _dmarc on your domain the way a receiving mail server does and tells you whether the record is present, whether it parses, and which policy it carries.

Wait, then read the result

Changes saved in the IONOS DNS section can take a few minutes up to a couple of hours to take effect. The saved record appears in the DNS section’s record list under the domain, alongside the domain’s other DNS entries.

Reopen the domain’s DNS section in IONOS and confirm the _dmarc TXT record shows the value exactly as saved, with no extra quote marks around it.

A scan run in the first minutes after saving can read as absent while nothing is wrong, because a resolver somewhere is still handing out its cached answer from before the record existed. If the scan still reports no DMARC after a couple of hours, go back to the nameserver check at the top of this page first and the host name second.

A record saved into a console that isn’t answering DNS for the domain is the most common reason a scan comes back unchanged, and the fix is to add the same record at the company the nameservers point to.

When the scan shows the record and its policy, you’re in the monitoring stage. Nothing about delivery has changed yet, and the first reports take a day or so to arrive.

Tightening from none to reject

p=none leaves delivery as it was and starts the reports arriving. Those reports are the only evidence you’ll get about what sends as your domain: your mail provider, a newsletter tool, an invoicing system, and whatever else somebody connected two years ago. Each report names the sending server, how many messages it sent, and whether SPF and DKIM passed for them. The DMARC piece explains how to read one and what a failing row means.

Without a record, a receiver that sees a message fail both checks has no instruction from you, so most deliver it anyway and nobody tells you. Of the 316,600,902 domains carrying a grade in the September 2026 census, 238,156,049 (75.2%) have no DMARC record at all. The monitoring stage has its own trap: of the domains whose DMARC record carries p=none, 33,651,068 (80.33%) have no rua= address, so they sit at none collecting nothing that would let them move.

Read the reports until every sender you recognise is passing and the failing rows are ones you don’t. Then change p=none to p=quarantine in the same field you saved it in, wait for a further round of reports to confirm your own mail still lands, and change it to p=reject. That last edit is the one that turns a monitoring record into an instruction receivers act on, and it takes the same minute in the IONOS console as the first one did.

Figures as of 5 September 2026, from the September 2026 edition of the defaults.exposed census. Census numbers move every month; the current values are on the census data page.