> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lettr.com/llms.txt
> Use this file to discover all available pages before exploring further.

# IONOS DNS Setup

> Add the DNS records Lettr needs in the IONOS Control Panel to verify your sending, inbound, tracking, and storage domains with DKIM and DMARC.

This guide walks you through adding the required DNS records for Lettr using IONOS's DNS management. IONOS is a web hosting and domain provider that offers DNS hosting for domains managed through its [IONOS Control Panel](https://my.ionos.com).

You will configure a **sending domain** (CNAME, DKIM TXT, and DMARC TXT records) and, optionally, an **inbound domain** (MX records), **tracking domain** (two CNAME records), and **storage domain** (CNAME and two TXT records).

***

## Sending Domain Setup

A sending domain authenticates your outgoing emails with DKIM and DMARC, ensuring they are delivered reliably and not marked as spam. This requires a CNAME record for domain verification, a TXT record for DKIM signing, and a TXT record for DMARC policy.

To create a sending domain in Lettr:

1. Select **Domains** in the navigation panel
2. Select **Sending Domains**
3. Click **Create Sending Domain**
4. Enter your desired sending subdomain (e.g. `mailing.company.com`)
5. Click **Create Domain**

<Tip>
  Use a subdomain (e.g. `mailing.company.com`) instead of the root domain (`company.com`). A subdomain provides proper
  reputation segmentation and is required if you also plan to receive emails with Lettr.
</Tip>

Click your new domain in the Sending Domains list.

This will display a list of DNS records that need to be configured. Keep this page open — you will need these values soon.

### Configure IONOS DNS

Log in to the [IONOS Control Panel](https://my.ionos.com) and click the **Domains & SSL** tile on the dashboard. Find the domain you want to configure, click the **three-dot menu** in the Actions column next to it, and select **DNS**.

<Tip>
  If your domain was purchased through IONOS or your nameservers already point to IONOS, skip nameserver
  configuration entirely. Your domain is already using IONOS's nameservers by default — proceed directly to adding the
  DNS records below.
</Tip>

<AccordionGroup>
  <Accordion title="Domain registered with a different registrar?">
    If you registered your domain elsewhere but want to manage DNS on IONOS, you must first **update the nameservers**
    at your registrar to the IONOS nameservers shown in your domain's DNS settings. IONOS assigns four nameservers per
    account in the format `ns1045.ui-dns.org`, `ns1045.ui-dns.de`, `ns1045.ui-dns.biz`, and `ns1045.ui-dns.com` — the
    number prefix (e.g. `1045`) varies by account. Use the exact values shown in your IONOS control panel.

    <Warning>Until the nameservers are updated, any records you add in IONOS will not resolve.</Warning>
  </Accordion>
</AccordionGroup>

### Add CNAME Record

The CNAME record verifies domain ownership with Lettr's email infrastructure.

Copy the CNAME values from Lettr to IONOS:

1. Click **Add record** in the DNS management page.
2. Select **CNAME** from the record type dropdown.
3. Set **Hostname** to the **Hostname** value from Lettr (without your domain suffix). For example, paste only `mailing`.
4. Set **Point to** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `mailing`, not `mailing.company.com`). If you paste the full hostname, the resulting record will resolve as
  `mailing.company.com.company.com`, which will fail verification.
</Info>

### Add TXT Record (DKIM)

The DKIM record adds a cryptographic signature to your outgoing emails, allowing recipients to verify they were sent by an authorized sender.

Copy the TXT values from Lettr to IONOS:

1. Click **Add record** in the DNS management page.
2. Select **TXT** from the record type dropdown.
3. Set **Host name** to the **Hostname** value from Lettr (without your domain suffix). For example, paste only `scph0126._domainkey.mailing`.
4. Set **Value** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `scph0126._domainkey.mailing`, not `scph0126._domainkey.mailing.company.com`).
</Info>

### Add TXT Record (DMARC)

The DMARC record tells receiving mail servers how to handle emails that fail authentication checks, protecting your domain from spoofing.

Copy the TXT values from Lettr to IONOS:

1. Click **Add record** in the DNS management page.
2. Select **TXT** from the record type dropdown.
3. Set **Host name** to the **Hostname** value from Lettr (without your domain suffix). For example, paste only `_dmarc.mailing`.
4. Set **Value** to the **Value** from Lettr (e.g. `v=DMARC1;p=none;`).
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `_dmarc.mailing`, not `_dmarc.mailing.company.com`).
</Info>

### Verify Your Sending Domain

After adding all three DNS records, go back to Lettr and click **Verify DNS Records**. DNS changes on IONOS propagate within about 1 hour in most cases, though external resolvers may take longer.

***

## Inbound Domain Setup

An inbound domain allows Lettr to receive emails on your behalf. This requires three MX records that direct incoming mail to Lettr's mail servers.

### Add Inbound Domain to Lettr

To create an Inbound domain in Lettr:

1. Select **Domains** in the navigation panel
2. Select **Inbound Domains**
3. Click **Create Inbound Domain**
4. Enter your desired inbound subdomain (e.g. `inbound.company.com`)
5. Click **Create Domain**.

Click on your new domain in the Inbound Domains list.

This will display the MX records that need to be configured.

### Add MX Records

MX records tell other mail servers where to deliver emails addressed to your domain.

Copy the MX values from Lettr to IONOS:

1. Click **Add record** in the DNS management page.
2. Select **MX** from the record type dropdown.
3. Set **Host name** to the **Hostname** value from Lettr (without your domain suffix). For example, paste only `inbound`.
4. Set **Points to** to `rx1.sparkpostmail.com`.
5. Set **Priority** to `10`.
6. Leave **TTL** at the default (3600).
7. Click **Save**.
8. Repeat this process for the second (`rx2.sparkpostmail.com`) and third (`rx3.sparkpostmail.com`) MX records, each with priority `10`.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `inbound`, not `inbound.company.com`).
</Info>

<Warning>
  All emails sent to the domain or subdomain where MX records are configured will be routed to Lettr. Use a dedicated
  subdomain (e.g. `inbound.company.com`) to avoid affecting your primary email.
</Warning>

### Verify Your Inbound Domain

After adding all three MX records, go back to Lettr and click **Verify DNS Records**. DNS changes on IONOS propagate within about 1 hour in most cases, though external resolvers may take longer.

***

## Tracking Domain Setup

A tracking domain allows Lettr to track email opens and link clicks using your own custom domain instead of the default Lettr tracking domain. This requires two CNAME records: one for the SSL certificate and one for routing tracking traffic to Lettr's infrastructure.

### Add Tracking Domain to Lettr

To create a Tracking domain in Lettr:

1. Select **Domains** in the navigation panel
2. Select **Tracking Domains**
3. Click **Create Tracking Domain**
4. Enter your desired tracking subdomain (e.g. `tracking.company.com`)
5. Click **Create Domain**

Click on your new domain in the Tracking Domains list.

This will display the CNAME records that need to be configured.

### Add SSL Certificate CNAME Record

The SSL Certificate CNAME record provisions an SSL certificate for your custom tracking domain, enabling secure HTTPS connections for tracked links.

Add the record in IONOS:

1. Click **Add record** in the DNS management page.
2. Select **CNAME** from the record type dropdown.
3. Set **Hostname** to the **Hostname** from Lettr (without your domain suffix).
4. Set **Point to** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `tracking`, not `tracking.company.com`).
</Info>

### Add Traffic CNAME Record

The Traffic CNAME record routes click and open tracking requests from your custom domain to Lettr's tracking servers.

Add the record in IONOS:

1. Click **Add record** in the DNS management page.
2. Select **CNAME** from the record type dropdown.
3. Set **Hostname** to the **Hostname** from Lettr (without your domain suffix).
4. Set **Point to** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `tracking`, not `tracking.company.com`).
</Info>

### Verify Your Tracking Domain

After adding both CNAME records, go back to Lettr and click **Verify DNS Records**.

***

## Storage Domain Setup

A storage domain lets you serve email assets (images, attachments) from your own custom domain instead of the default Lettr storage URL. This requires two TXT records for certificate validation and ownership verification, and a CNAME record for routing asset requests to Lettr's storage infrastructure.

### Add Storage Domain to Lettr

To create a Storage domain in Lettr:

1. Select **Domains** in the navigation panel
2. Select **Storage Domains**
3. Click **Create Storage Domain**
4. Enter your desired storage subdomain (e.g. `assets.company.com`)
5. Click **Create Domain**

Click on your new domain in the Storage Domains list.

This will display the TXT and CNAME records that need to be configured.

### Add TXT Record (Certificate Validation)

The Certificate Validation TXT record provisions an SSL certificate for your custom storage domain, enabling secure HTTPS delivery of email assets.

Add the record in IONOS:

1. Click **Add record** in the DNS management page.
2. Select **TXT** from the record type dropdown.
3. Set **Host name** to the **Hostname** from Lettr (without your domain suffix).
4. Set **Value** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion, just as with the CNAME record above.</Info>

### Add TXT Record (Hostname Pre-validation)

The Hostname Pre-validation TXT record verifies ownership of the storage domain before Lettr provisions a custom hostname for it.

Add the record in IONOS:

1. Click **Add record** in the DNS management page.
2. Select **TXT** from the record type dropdown.
3. Set **Host name** to the **Hostname** from Lettr (without your domain suffix).
4. Set **Value** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion, just as with the CNAME record above.</Info>

### Add CNAME Record (Domain Routing)

The Domain Routing CNAME record routes asset requests from your custom domain to Lettr's storage infrastructure.

Add the record in IONOS:

1. Click **Add record** in the DNS management page.
2. Select **CNAME** from the record type dropdown.
3. Set **Hostname** to the **Hostname** from Lettr (without your domain suffix).
4. Set **Point to** to the **Value** from Lettr.
5. Leave **TTL** at the default (3600).
6. Click **Save**.

<Info>
  IONOS automatically appends your domain to the hostname. Always paste only the subdomain portion (e.g.
  `assets`, not `assets.company.com`).
</Info>

### Verify Your Storage Domain

After adding all three records, go back to Lettr and click **Verify DNS Records**.

***

## Troubleshooting

<AccordionGroup>
  <Accordion title="Domain Suffix Not Omitted">
    IONOS automatically appends your domain to the **Hostname** / **Host name** field. If you paste the full hostname
    (e.g. `mailing.company.com`), the resulting record will resolve as `mailing.company.com.company.com`, which will
    fail verification.

    Always paste only the subdomain portion (e.g. `mailing`, `scph0126._domainkey.mailing`, `_dmarc.mailing`).
  </Accordion>

  <Accordion title="Records Not Propagating">
    IONOS applies DNS changes immediately on their side, but external resolvers may take up to 1 hour to pick up the
    changes (and in rare cases, ISPs with long cache times may take longer). If verification fails after adding records,
    check the following:

    * **Wait at least 1 hour** before your first verification attempt.
    * **Confirm the records exist** using command-line tools:

    ```bash theme={null}
    # Check CNAME record
    dig CNAME mailing.yourdomain.com +short

    # Check DKIM record
    dig TXT scph0126._domainkey.mailing.yourdomain.com +short

    # Check DMARC record
    dig TXT _dmarc.mailing.yourdomain.com +short

    # Check MX records (inbound)
    dig MX inbound.yourdomain.com +short

    # Check tracking domain CNAME
    dig CNAME track.yourdomain.com +short

    # Check storage domain CNAME
    dig CNAME assets.yourdomain.com +short
    ```

    * **Use a web tool** like [dnschecker.org](https://dnschecker.org) to verify propagation across multiple DNS servers worldwide.
  </Accordion>

  <Accordion title="Nameservers Not Pointing to IONOS">
    If your records are saved in IONOS but not resolving, confirm that your domain is using IONOS's nameservers. You can
    check this with:

    ```bash theme={null}
    dig NS yourdomain.com +short
    ```

    The output should include IONOS nameservers in the format `ns####.ui-dns.org`, `ns####.ui-dns.de`,
    `ns####.ui-dns.biz`, and `ns####.ui-dns.com` (where `####` is a number unique to your account). Your exact
    nameservers are shown in the IONOS Control Panel under **Domains & SSL** → your domain's DNS settings. If the output
    shows a different provider's nameservers, update them at your domain registrar.
  </Accordion>

  <Accordion title="CNAME at Root Domain Not Supported">
    IONOS does not allow CNAME records at the root of a domain (e.g. `company.com`). You must use a subdomain for your
    sending domain (e.g. `mailing.company.com`). This is also a DNS protocol limitation — CNAME records cannot coexist
    with other record types at the same name.
  </Accordion>

  <Accordion title="Conflicting Service-Managed Records">
    If you have IONOS-hosted services active on your domain (e.g. Microsoft 365, IONOS webmail, WordPress hosting),
    IONOS manages some DNS records automatically. Adding records that conflict with service-managed entries may cause
    errors or silent overwrites. Check for existing A, CNAME, or MX records on the same hostname before adding new ones,
    and remove any conflicting entries first.
  </Accordion>

  <Accordion title="Wrong Record Type">
    A common mistake is selecting the wrong type from the record type dropdown:

    | Record                          | Correct Type |
    | ------------------------------- | ------------ |
    | Sending verification            | CNAME        |
    | DKIM                            | TXT          |
    | DMARC                           | TXT          |
    | Inbound mail                    | MX           |
    | Tracking SSL certificate        | CNAME        |
    | Tracking traffic                | CNAME        |
    | Storage certificate validation  | TXT          |
    | Storage hostname pre-validation | TXT          |
    | Storage domain routing          | CNAME        |
  </Accordion>

  <Accordion title="DKIM Value Truncated">
    The DKIM TXT value is a long string. After saving the record, re-open the DNS management page and confirm the full
    value is displayed. If it appears truncated, delete the record and re-add it, pasting the full value carefully into
    the **Value** field.

    If IONOS rejects the value due to length, try splitting the `p=` portion into two quoted strings separated by a
    space: `"v=DKIM1; k=rsa; p=firsthalf" "secondhalf"`. Paste both quoted strings together into the **Value** field.
  </Accordion>

  <Accordion title="When to Contact Support">
    If your DNS records are correctly configured (confirmed with `dig` or dnschecker.org) and verification still fails after
    48 hours, contact Lettr support at **[support@lettr.com](mailto:support@lettr.com)** or through the in-app chat. Include your domain name and the
    output of the `dig` commands above.
  </Accordion>
</AccordionGroup>

***

## Related Topics

<CardGroup cols={2}>
  <Card title="Sending Domains" icon="paper-plane" href="/learn/domains/sending-domains">
    Learn about sending domain setup, SPF, DKIM, and DMARC.
  </Card>

  <Card title="Inbound Domains" icon="inbox" href="/learn/domains/inbound-domains">
    Configure MX records to receive emails with Lettr.
  </Card>

  <Card title="Tracking Domains" icon="link" href="/learn/domains/tracking-domains">
    Set up a custom tracking domain for click and open tracking.
  </Card>

  <Card title="Storage Domains" icon="hard-drive" href="/learn/domains/storage-domains">
    Serve email assets from your own custom domain.
  </Card>

  <Card title="Domains Overview" icon="globe" href="/learn/domains/introduction">
    Understand domain types and how they work in Lettr.
  </Card>

  <Card title="Domain Verification Failures" icon="circle-exclamation" href="/knowledge-base/troubleshooting/domain-verification">
    Troubleshoot common DNS configuration and propagation issues.
  </Card>
</CardGroup>