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How do I set up my custom sending domain for my organization or my channel?

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A verified custom sending domain lets you send newsletters from your own email address and protects your deliverability. You can set one up at the organization level (applies to all channels) or the channel level.

Before you start

Section titled “Before you start”
  • Use a subdomain (for example, mail in mail.yourdomain.com). This keeps spam reports from affecting your root domain’s reputation.
  • Your sender email and reply-to email should share the same root domain (for example, @mail.yourdomain.com and @reply.yourdomain.com).
  • Manual replies (including a person’s out-of-office message) go to your reply-to address; some server-triggered automated replies go to the sender email.

Where to add your domain

Section titled “Where to add your domain”
  • Organization level — open your organization’s Settings → Newsletters; the Sending Domain section is there. The domain applies to every channel under the organization.
  • Channel level — open the channel’s Settings → Sending emails; the Sending Domain section is at the top. The steps below are the same.

Add and verify the domain

Section titled “Add and verify the domain”

Letterhead sends via SparkPost. In the Sending Domain section:

  1. Enter your sending subdomain (for example, mail.yourdomain.com).
  2. Letterhead shows the DNS records to publish. Copy each Hostname and Value into your DNS provider (GoDaddy, Cloudflare, Namecheap, etc.):
    • CNAME record
    • DKIM record (a TXT record)
    • DMARC record (a TXT record)
  3. Also confirm your SPF record includes SparkPost (see below).
  4. Back in Letterhead’s Sending Domain section, click Verify domain.
  5. When the records are correct, each card shows a green Verified label instead of Verification needed.

Verification can take anywhere from a couple of minutes to a few hours. If your domain won’t verify, double-check the values; if problems persist, contact [email protected].

DNS provider quirks: some providers require a trailing dot on values (for example, sparkpostmail.com.) so your root domain isn’t appended, and some only want the subdomain portion as the hostname (for example, scph****._domainkey instead of the full hostname).

CNAME record

Section titled “CNAME record”

Create a new record with your DNS provider:

  • Record Type: CNAME
  • Hostname: the CNAME hostname copied from Letterhead (many providers only need the subdomain part, e.g. mail)
  • Value: the CNAME value copied from Letterhead (e.g. sparkpostmail.com)

DKIM record

Section titled “DKIM record”

Create a new record:

  • Record Type: TXT
  • Hostname: the DKIM hostname from Letterhead — for a subdomain it looks like scph0####._domainkey.mail.yourdomain.com
  • Value: the DKIM value from Letterhead (starts with v=DKIM1; k=rsa; h=sha256;...)

SPF record (required for deliverability)

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SPF tells mailbox providers which servers may send email for your domain. Because Letterhead sends through SparkPost, your SPF record must include SparkPost — otherwise Gmail and other providers may reject or rate-limit your messages, and your newsletters may land in spam.

  • You should only have one SPF record per domain. If one exists (it starts with v=spf1), merge SparkPost into it rather than creating a second record: add include:sparkpostmail.com to the existing value and save. Don’t replace your existing record unless your IT team says to.
  • If none exists, create a TXT record on your root domain (hostname usually @ or blank) that includes include:sparkpostmail.com alongside any other services that legitimately send from your domain, for example:
v=spf1 include:_spf.google.com include:sparkpostmail.com ~all

DMARC record

Section titled “DMARC record”

DMARC tells receiving mail servers how to handle messages that claim to be from your domain but fail authentication, protecting you from spoofing.

  • Record Type: TXT
  • Hostname: _dmarc on your sending subdomain — for example, _dmarc.mail.yourdomain.com
  • Value: must include v=DMARC1 and a policy tag (p=none, p=quarantine, or p=reject). Start new records with p=none so legitimate mail isn’t accidentally quarantined while you identify SPF/DKIM issues. We strongly recommend the rua tag so you receive aggregate reports:
v=DMARC1; p=none; rua=mailto:[email protected]

Separate tags with semicolons; rua and ruf accept multiple comma-separated addresses. You’ll begin receiving DMARC reports at that address, which help you spot authentication issues and malicious use of your domain. Advanced tags exist but aren’t recommended for initial setup.

Connecting an external ESP instead

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If you sync audience data from another provider rather than (or alongside) sending through Letterhead:

  • Mailchimp — enter your API Key (Mailchimp: Profile → Extras → API Keys), Audience (List) ID (Audience → Settings → Audience name and defaults), and Server Prefix (the us6 in https://us6.api.mailchimp.com/).
  • Iterable — enter your Iterable API Key (Iterable: Integrations → API Keys).

See Working in Integrations for more on connected services.

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Still can’t find what you need? Contact support.