How Email Authentication (SPF, DKIM, and DMARC) Impacts Deliverability

When it comes to email marketing, getting your messages delivered to the inbox—not the spam folder—is everything.
One of the most important factors that determines whether your emails make it to your audience is authentication.

If you’ve heard terms like SPF, DKIM, or DMARC and wondered what they actually mean, this guide will break them down in plain language and explain why they’re essential for your home care agency’s email success.

Email authentication is the digital “proof” that your messages are legitimate and come from your domain—not from a spammer pretending to be you.

It’s a set of DNS records (domain settings) that tell inbox providers like Gmail, Outlook, and Yahoo:

• “Yes, this sender is authorized to send email from this domain.”

• “No, this isn’t spoofed, fraudulent, or altered in transit.”

Without proper authentication, your emails can look suspicious to spam filters, even if you’re sending to valid contacts who opted in.

SPF (Sender Policy Framework)

SPF is like a guest list for your email domain.
It specifies which mail servers are allowed to send messages on behalf of your domain.

When an inbox receives your message, it checks your SPF record to confirm:

“Is this email coming from a server that’s authorized to send mail for this domain?”

If yes, the message passes. If not, it may be flagged or rejected.

✅ Best practice: Always include any marketing or CRM platforms (like CareFunnels or Mailgun) in your SPF record to authorize them to send email for you.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to each outgoing message using encryption.

This signature verifies that the email’s content hasn’t been changed and that it truly came from your domain. It’s like a wax seal on a letter—confirming authenticity and integrity.

✅ Best practice: Ensure your marketing platform uses a unique DKIM key connected to your domain (not just their shared default). CareFunnels automatically sets this up for all authenticated sending domains.

DMARC (Domain-based Message Authentication, Reporting & Conformance)

DMARC ties SPF and DKIM together. It tells inbox providers how to handle emails that fail authentication checks.

For example, your DMARC policy might say:

• “If SPF and DKIM fail, send these messages to spam.”

• “If failures happen often, send me reports so I can investigate.”

This adds an extra layer of protection against phishing and spoofing attacks while reinforcing your domain’s credibility.

✅ Best practice: Start with a monitoring-only policy (p=none) to collect data, then move to a stricter policy (p=quarantine or p=reject) once authentication is fully validated.

Inbox providers rely on authentication to decide whether your messages are trustworthy. When SPF, DKIM, and DMARC are correctly configured:

• Your domain gains a strong reputation as a verified sender

• Your emails are less likely to land in spam or promotions folders

• You’re protected from bad actors impersonating your brand

• Your overall deliverability improves dramatically over time

For CareFunnels users, these protocols are automatically configured through Mailgun’s enterprise-level infrastructure to ensure high inbox placement and sender trust.

Even small errors can harm deliverability. The most frequent issues include:

• Missing or incomplete SPF records

• Using multiple SPF records (only one is allowed per domain)

• Forgetting to update DNS records when switching email platforms

• Using shared DKIM keys instead of domain-specific ones

• Not monitoring DMARC reports for authentication failures

If you’re unsure whether your domain is properly configured, Home Care Marketing Pros can review your DNS records to confirm everything is set up correctly.

Think of your email reputation like your credit score—it determines how much trust inbox providers give you.

Authentication builds that reputation over time by proving you’re a consistent, safe, and verified sender.
This is especially important for:

• Agencies using CareFunnels for automated follow-ups and newsletters

• Multi-location businesses sending higher email volumes

• Recruitment campaigns with ongoing email outreach

Without authentication, even great content can underperform simply because it looks unverified.

Proper email authentication isn’t just technical—it’s foundational to your marketing success.

When SPF, DKIM, and DMARC are configured correctly:

• You build trust with inbox providers

• You protect your domain reputation

• You achieve higher inbox placement and engagement

At Home Care Marketing Pros, we configure and manage these records for all CareFunnels clients to ensure secure, compliant, and high-performing email delivery—so your messages reach the families, caregivers, and leads who matter most.