What Is SPF, DKIM, and DMARC?
SPF, DKIM, and DMARC are three email authentication standards set up as records in your domain's DNS settings. Together they prove to inbox providers that emails using your domain are legitimate and have not been altered.
SPF (Sender Policy Framework) lists the servers allowed to send email for your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to each email. DMARC (Domain-based Message Authentication, Reporting, and Conformance) tells providers what to do when an email fails those checks and sends you reports.
Why SPF, DKIM, and DMARC Matters for Northern Indiana & Michiana Businesses
Without authentication, your emails are more likely to land in spam, and scammers can more easily send fake emails that look like they come from your business. That risk matters for any Northern Indiana business sending invoices, appointment reminders, or newsletters.
Since 2024, Gmail and Yahoo require authentication for bulk senders, and Gmail asks senders of 5,000 or more daily messages to its users to set up SPF, DKIM, and DMARC. Smaller senders also benefit, since authenticated mail earns more trust.
How SPF, DKIM, and DMARC Works
- SPFA DNS record lists approved sending services, such as your email host and newsletter platform.
- DKIMYour sending service signs each email, and receivers check the signature against a public key in your DNS.
- DMARCA DNS policy tells receivers to monitor, quarantine, or reject failing mail and send reports.
- AlignmentDMARC checks that the visible "From" domain matches the authenticated domain.
- ReportingDMARC reports show who is sending email using your domain.
A Local Example
A Goshen insurance agency sends policy reminders through its agency software, newsletters through Mailchimp, and everyday email through Microsoft 365. Only Microsoft 365 is included in its SPF record, so many newsletters fail checks. After updating SPF, enabling DKIM for each service, and adding a DMARC record in monitoring mode, its emails pass authentication and reach more inboxes.
After reviewing DMARC reports for a few weeks to confirm every legitimate service passes, the agency strengthens its policy to quarantine, which helps protect clients from spoofed emails.
Getting Started With SPF, DKIM, and DMARC
List every service that sends email using your domain: your email host, newsletter platform, CRM, booking tools, invoicing software, and website forms. Each one needs to be included in SPF and set up with DKIM.
Then check your current records with a free DNS or DMARC lookup tool. Add or update SPF with all services, enable DKIM in each platform, and publish a DMARC record starting with a monitoring policy (p=none). Review DMARC reports, fix any legitimate services that fail, and then move toward a stronger policy over time.
Quick Wins to Improve Your Email Authentication
- List every service that sends email for your domain
- Combine all senders into one SPF record
- Turn on DKIM signing in each email platform
- Publish a DMARC record, starting with monitoring
- Review DMARC reports before tightening your policy
What to Watch For
- Multiple SPF records. A domain should have only one SPF record; combine services into it.
- SPF lookup limits. SPF allows up to 10 DNS lookups; too many includes cause failures.
- Moving too fast. Jumping to a reject policy before fixing all senders can block real email.
- New tools. Add each new sending service to your records when you adopt it.
SPF, DKIM, and DMARC FAQ
Do I need all three?
Yes. They work together, and major inbox providers expect all three from bulk senders.
Where do I add these records?
In your domain's DNS settings, usually through your domain registrar or hosting provider.
What DMARC policy should I start with?
Start with p=none to monitor, then move to quarantine and reject once all legitimate senders pass.
Will authentication alone fix spam problems?
It is the foundation. List quality, engagement, and content also shape inbox placement.
Put It to Work
Want your emails trusted by every inbox? Riley will check your SPF, DKIM, and DMARC setup and fix what is missing.
