What is Sending Domain?
A sending domain is the domain used in the From address of emails, configured with DNS records to authenticate the sender and establish reputation with inbox providers.
A sending domain (also called a "from domain" or "mail-from domain") is the domain that appears in the From address of your emails and is used by inbox providers to evaluate authentication and reputation. It's the domain your recipients see and associate with your emails.
Setting up a sending domain involves adding DNS records: an SPF record authorizing your email provider to send on behalf of the domain, a DKIM record for cryptographic signature verification, and optionally a DMARC record defining your authentication policy. Many email providers also require a CNAME record for tracking link branding.
For SaaS platforms using white label email, each customer typically has their own sending domain. This means the platform needs to manage domain onboarding, DNS verification, and authentication for potentially hundreds or thousands of customer domains.
Why Sending Domain Matters
Your sending domain is your email identity. Inbox providers track reputation per domain, so using a properly authenticated sending domain is essential for deliverability. For platforms, managing customer sending domains at scale—onboarding, verification, monitoring—is one of the most operationally complex aspects of email infrastructure.
How Ark Handles Sending Domain
Ark simplifies sending domain management for platforms. Add a customer's domain via the API, and Ark generates all required DNS records with setup instructions tailored to common DNS providers (Cloudflare, GoDaddy, Route53, etc.). Ark monitors domain health continuously and alerts you if authentication breaks.
Frequently Asked Questions
What is a sending domain?
A sending domain is the domain in your email's From address (e.g., [email protected] uses 'yourcompany.com' as the sending domain). It must be authenticated with DNS records (SPF, DKIM) to ensure inbox delivery.
Should each customer have their own sending domain?
Yes, for white label email. Each customer should send from their own domain so emails appear to come from their brand. This also isolates reputation: each domain builds its own reputation independently with inbox providers.
Can I use a subdomain as a sending domain?
Yes, subdomains (like mail.yourcompany.com) are commonly used as sending domains. This protects your root domain's reputation and lets you separate transactional and marketing email reputation. Each subdomain builds its own independent reputation.
Related Terms
Domain Authentication
Domain authentication is the process of configuring DNS records (SPF, DKIM, DMARC) to prove to inbox...
DNS Records
DNS records for email are entries in your domain's DNS that configure mail delivery (MX), sender aut...
SPF
Sender Policy Framework (SPF) is an email authentication method that specifies which mail servers ar...
DKIM
DomainKeys Identified Mail (DKIM) is an email authentication method that uses cryptographic signatur...
White Label Email
White label email is a service that lets platforms send email on behalf of their customers using the...
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