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This guide walks you through adding the required DNS records for Lettr using Strato’s DNS management. Strato is a German web hosting and domain provider that offers DNS hosting for domains managed through its Strato Control Panel. 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).

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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
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.
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.

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Configure Strato DNS

Log in to the Strato Control Panel and navigate to Domains → Domainverwaltung (Domain Management). Click the gear icon next to your domain and select the DNS tab to open the DNS editor.
If your domain was purchased through Strato or your nameservers already point to Strato, skip nameserver configuration entirely. Your domain is already using Strato’s nameservers by default — proceed directly to adding the DNS records below.
If you registered your domain elsewhere but want to manage DNS on Strato, you must first update the nameservers at your registrar to Strato’s nameservers:
  • ns1.strato.de
  • ns2.strato.de
  • ns4.strato.de
Until the nameservers are updated, any records you add in Strato will not resolve.

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Add CNAME Record

The CNAME record verifies domain ownership with Lettr’s email infrastructure. Copy the CNAME values from Lettr to Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to CNAME.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix. For example, paste only mailing.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato automatically appends your domain to the Präfix field. Always paste only the subdomain portion (e.g. mailing, not mailing.company.com).

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to TXT.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix. For example, paste only scph0126._domainkey.mailing.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
DKIM records are case-sensitive. Copy the value exactly using the copy icon in your Lettr dashboard. Strato supports multiple TXT records on the same hostname, so this record will not conflict with existing TXT records.

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to TXT.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix. For example, paste only _dmarc.mailing.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field (e.g. v=DMARC1;p=none;).
  5. Click Einstellungen übernehmen (Apply settings).

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Verify Your Sending Domain

After adding all three DNS records, go back to Lettr and click Verify DNS Records. DNS propagation on Strato can take up to 24 hours, though it typically completes within a few minutes to a few hours.

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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.

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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.

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Add MX Records

MX records tell other mail servers where to deliver emails addressed to your domain. Strato uses a dedicated MX configuration dialog. In the DNS tab, click verwalten (manage) next to the MX record row, then enable Eigener Mailserver (Own mail server) to configure custom MX entries. Add the MX records for your inbound subdomain:
  1. In the MX configuration dialog, enable Eigener Mailserver (Own mail server).
  2. Enter rx1.sparkpostmail.com. (with trailing dot) as the mail server hostname.
  3. Set Priorität (Priority) to 10.
  4. Click + Weiteren Record erstellen (Create another record) and repeat for rx2.sparkpostmail.com. and rx3.sparkpostmail.com., each with priority 10.
  5. Click Einstellungen übernehmen (Apply settings).
Strato requires a trailing dot on MX record hostnames (e.g. rx1.sparkpostmail.com.). Without it, the record may not resolve correctly.
Adding MX records to a domain or subdomain will route all incoming email for that address to Lettr. Enabling Eigener Mailserver disables Strato’s mail handling for that subdomain. Use a dedicated subdomain (e.g. inbound.company.com) to avoid affecting your primary email.

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Verify Your Inbound Domain

After adding all three MX records, go back to Lettr and click Verify DNS Records. DNS propagation on Strato can take up to 24 hours, though it typically completes within a few minutes to a few hours.

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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.

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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.

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to CNAME.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato automatically appends your domain to the Präfix field. Always paste only the subdomain portion (e.g. tracking, not tracking.company.com).
Strato does not allow a CNAME record to coexist with other record types (A, MX, TXT) on the same hostname. If the subdomain already has other records, you may need to remove them or use a different subdomain.

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to CNAME.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato automatically appends your domain to the Präfix field. Always paste only the subdomain portion (e.g. tracking, not tracking.company.com).

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Verify Your Tracking Domain

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

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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.

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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.

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to TXT.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato automatically appends your domain to the Präfix field. Always paste only the subdomain portion (e.g. assets, not assets.company.com).

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to TXT.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato supports multiple TXT records on the same hostname — add each record separately using the + Weiteren Record erstellen button.

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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 Strato:
  1. In the DNS editor, click + Weiteren Record erstellen (Create another record).
  2. Set Typ (Type) to CNAME.
  3. Copy the Hostname from Lettr and paste it into the Präfix (Prefix) field — without your domain suffix.
  4. Copy the Value from Lettr and paste it into the Wert (Value) field.
  5. Click Einstellungen übernehmen (Apply settings).
Strato automatically appends your domain to the Präfix field. Always paste only the subdomain portion (e.g. assets, not assets.company.com).

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Verify Your Storage Domain

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

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Troubleshooting

Strato automatically appends your domain to the Präfix (Prefix) 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).
DNS propagation on Strato can take up to 24 hours. If verification fails after adding records, check the following:
  • Wait at least 2–4 hours before your first verification attempt.
  • Confirm the records exist using command-line tools:
# 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 to verify propagation across multiple DNS servers worldwide.
If your records are saved in Strato but not resolving, confirm that your domain is using Strato’s nameservers. You can check this with:
dig NS yourdomain.com +short
The output should include Strato nameservers (e.g. ns1.strato.de, ns2.strato.de, ns4.strato.de). If it shows a different provider’s nameservers, update them at your domain registrar.
Strato does not allow a CNAME record to coexist with other record types (A, MX, TXT) on the same hostname. Adding a CNAME will deactivate all other DNS settings for that exact subdomain. If you need CNAME records for Lettr on a subdomain that already has other records, use a different subdomain or remove the conflicting records first.Additionally, CNAME records are not available at the root domain (e.g. company.com) in Strato — you must always use a subdomain.
A common mistake is selecting the wrong record type in the Typ dropdown:
RecordCorrect Type
Sending verificationCNAME
DKIMTXT
DMARCTXT
Inbound mailMX
Tracking SSL certificateCNAME
Tracking trafficCNAME
Storage certificate validationTXT
Storage hostname pre-validationTXT
Storage domain routingCNAME
Strato configures its own mail server for domains by default. To add custom MX records, navigate to the MX configuration dialog (click verwalten next to MX records in the DNS tab) and enable Eigener Mailserver (Own mail server). Without this step, Strato will not allow custom MX entries.Also ensure that mail server hostnames include a trailing dot (e.g. rx1.sparkpostmail.com.).
The DKIM TXT value is a long string. After saving the record, re-open the DNS editor and confirm the full value is displayed. If it appears truncated, delete the record and re-add it, pasting the full value carefully.
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 or through the in-app chat. Include your domain name and the output of the dig commands above.

Sending Domains

Learn about sending domain setup, SPF, DKIM, and DMARC.

Inbound Domains

Configure MX records to receive emails with Lettr.

Tracking Domains

Set up a custom tracking domain for click and open tracking.

Storage Domains

Serve email assets from your own custom domain.

Domains Overview

Understand domain types and how they work in Lettr.

Domain Verification Failures

Troubleshoot common DNS configuration and propagation issues.