Skip to main content
This guide walks you through adding the required DNS records for Lettr using Microsoft Azure DNS. Azure DNS is a reliable, fast DNS service built on Microsoft’s global network of name servers, managed through the Azure Portal. 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
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.

​
Configure Azure DNS

Log in to the Azure Portal and navigate to All services in the left-hand menu. Search for DNS zones to view your zones, and select the zone that matches your domain.
If your domain was purchased through Azure or your nameservers already point to Azure DNS, skip nameserver configuration entirely. Your domain is already using Azure DNS’s nameservers by default — proceed directly to adding the DNS records below.
If you registered your domain elsewhere but want to manage DNS on Azure, you must first create a DNS zone in Azure DNS and then update the nameservers at your registrar to Azure’s nameservers shown in the zone overview.Azure DNS zone overview showing nameserver records
Until the nameservers are updated, any records you add in Azure DNS will not resolve.

​
Add CNAME Record

The CNAME record verifies domain ownership with Lettr’s email infrastructure. Add the record in Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field. For example, paste only mailing, not mailing.company.com.
  3. Set Type to CNAME.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Alias field.
  6. Click Add.
Azure DNS record set form for adding a sending domain CNAME record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. mailing, not mailing.company.com).

​
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. Add the record in Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field. For example, paste only scph0126._domainkey.mailing.
  3. Set Type to TXT.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Value field.
  6. Click Add.
Azure DNS record set form for adding a DKIM TXT record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. scph0126._domainkey.mailing, not scph0126._domainkey.mailing.company.com).
DKIM values are long strings. After saving, re-open the record set to confirm the full value was stored correctly. If it appears truncated, delete and re-add the record.

​
Add TXT Record (DMARC)

The DMARC record tells receiving mail servers how to handle emails that fail authentication checks, protecting your domain from spoofing. Add the record in Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field. For example, paste only _dmarc.mailing.
  3. Set Type to TXT.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Value field.
  6. Click Add.
Azure DNS record set form for adding a DMARC TXT record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. _dmarc.mailing, not _dmarc.mailing.company.com).

​
Verify Your Sending Domain

After adding all three DNS records, go back to Lettr and click Verify DNS Records. DNS propagation can take up to 24–48 hours, though it typically completes within a few minutes.

​
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. Add the MX record set in Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field. For example, paste only inbound.
  3. Set Type to MX.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Under MX Records, enter 10 for Preference and rx1.sparkpostmail.com for Mail exchange.
  6. Add two more rows: 10 / rx2.sparkpostmail.com and 10 / rx3.sparkpostmail.com.
  7. Click Add.
Azure DNS record set form for adding MX records for inbound mail
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. inbound, not inbound.company.com).
Adding MX records to a domain or subdomain will route all incoming email for that address to Lettr. Use a dedicated subdomain (e.g. inbound.company.com) to avoid affecting your primary email.

​
Verify Your Inbound Domain

After adding all three MX records, go back to Lettr and click Verify DNS Records. DNS propagation can take up to 24–48 hours, though it typically completes within a few minutes.

​
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 Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field.
  3. Set Type to CNAME.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Alias field.
  6. Click Add.
Azure DNS record set form for adding the SSL certificate CNAME record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. tracking, not tracking.company.com).

​
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 Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field.
  3. Set Type to CNAME.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Alias field.
  6. Click Add.
Azure DNS record set form for adding the traffic routing CNAME record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. tracking, not tracking.company.com).

​
Verify Your Tracking Domain

After adding both CNAME records, go back to Lettr and click Verify DNS Records. DNS propagation can take up to 24–48 hours, though it typically completes within a few minutes.

​
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 Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field.
  3. Set Type to TXT.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Value field.
  6. Click Add.
Azure DNS record set form for adding the certificate validation TXT record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. storage, not storage.company.com).

​
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 Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field.
  3. Set Type to TXT.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Value field.
  6. Click Add.
Azure DNS record set form for adding the hostname pre-validation TXT record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. storage, not storage.company.com).

​
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 Azure DNS:
  1. Click + Add in your DNS zone.
  2. Enter the Hostname from Lettr (without your domain suffix) into the Name field.
  3. Set Type to CNAME.
  4. Leave TTL and TTL unit at their defaults (1 Hour).
  5. Enter the Value from Lettr into the Alias field.
  6. Click Add.
Azure DNS record set form for adding the domain routing CNAME record
Azure DNS automatically appends your zone name to the record name. Always paste only the subdomain portion (e.g. storage, not storage.company.com).

​
Verify Your Storage Domain

After adding all three records, go back to Lettr and click Verify DNS Records. DNS propagation can take up to 24–48 hours, though it typically completes within a few minutes.

​
Using Azure CLI

You can also add records using the Azure CLI. Replace <resource-group> and <zone-name> with your own values. 
# Add CNAME record for sending domain verification
az network dns record-set cname set-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name mailing \
  --ttl 3600 \
  --cname <value-from-lettr>

# Add TXT record for DKIM
az network dns record-set txt add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name "scph0126._domainkey.mailing" \
  --value "v=DKIM1;k=rsa;h=sha256;p=MIGf..."

# Add TXT record for DMARC
az network dns record-set txt add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name "_dmarc.mailing" \
  --value "v=DMARC1;p=none;"

# Add MX records for inbound (run once per exchange)
az network dns record-set mx add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name inbound \
  --exchange rx1.sparkpostmail.com \
  --preference 10

az network dns record-set mx add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name inbound \
  --exchange rx2.sparkpostmail.com \
  --preference 10

az network dns record-set mx add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name inbound \
  --exchange rx3.sparkpostmail.com \
  --preference 10

# Add CNAME records for tracking domain
az network dns record-set cname set-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name <ssl-cert-hostname-from-lettr> \
  --ttl 3600 \
  --cname <ssl-cert-value-from-lettr>

az network dns record-set cname set-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name tracking \
  --ttl 3600 \
  --cname <traffic-value-from-lettr>

# Add TXT and CNAME records for storage domain
az network dns record-set txt add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name <cert-validation-hostname-from-lettr> \
  --value "<cert-validation-value-from-lettr>"

az network dns record-set txt add-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name <hostname-prevalidation-hostname-from-lettr> \
  --value "<hostname-prevalidation-value-from-lettr>"

az network dns record-set cname set-record \
  --resource-group <resource-group> \
  --zone-name example.com \
  --record-set-name assets \
  --ttl 3600 \
  --cname <domain-routing-value-from-lettr>

​
Troubleshooting

Ensure you have the DNS Zone Contributor role or equivalent permissions on the DNS zone resource in Azure.
Azure DNS typically propagates within minutes, but in some cases it can take longer. If verification fails after adding records, check the following:
  • Wait at least 30 minutes 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.
Alternatively, you can use the Azure CLI to verify records directly:
az network dns record-set list \
  --resource-group <resource-group> \
  --zone-name yourdomain.com \
  --output table
If your records are saved in Azure DNS but not resolving, confirm that your domain registrar is pointing to Azure’s nameservers. You can check this with:
dig NS yourdomain.com +short
The output should include the four Azure nameservers shown in your DNS zone overview (e.g. ns1-xx.azuredns.com). If it shows a different provider’s nameservers, update them at your domain registrar.
A common mistake is selecting the wrong type when creating the record set:
RecordCorrect Type
Sending verificationCNAME
DKIMTXT
DMARCTXT
Inbound mailMX
Tracking SSL certificateCNAME
Tracking trafficCNAME
Storage certificate validationTXT
Storage hostname pre-validationTXT
Storage domain routingCNAME
The DKIM TXT value is a long string. After saving the record set in Azure, re-open it to confirm the full value was stored. 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.