Email sender guidelines: Why DMARC, DKIM, and SPF matter

Major email providers such as Google, Yahoo, and Outlook have introduced stricter sender requirements to reduce spam, phishing, and spoofing, and to improve overall email security. These changes mean configuring SPF, DKIM, and DMARC is no longer optional, but essential. In this post, we break down what’s changed, why it matters, and how to ensure your emails continue landing in inboxes, not spam folders.

Over the past year, major email providers like Google (Gmail), Microsoft (Outlook), and Yahoo have tightened their requirements for email senders. If you're a business owner or email marketer, you've probably already felt the impact—whether in reduced deliverability, bounced messages, or even being flagged as spam.

These changes aren't just technical checkboxes—they’re part of a global push to reduce spam, phishing, and spoofing. And if your emails aren't aligned with the latest authentication standards, they might never reach your customers’ inboxes.

At Serversaurus, we’re here to help you navigate these changes while staying true to our values: secure, reliable, and environmentally positive Australian web hosting.

The key difference now is enforcement. Major email providers are requiring stricter sender authentication to accept your messages. That means:

• SPF (Sender Policy Framework) is no longer optional.
• DKIM (DomainKeys Identified Mail) must be properly configured.
• DMARC (Domain-based Message Authentication, Reporting & Conformance) is now a critical layer of protection which is no longer optional for bulk senders. A bulk sender is sending 5,000 or more email weekly.

If your domain doesn’t meet these criteria, your emails could be rejected or routed to spam—regardless of your content or sender reputation.

Together, these authentication policies form a "triple-lock" of email authentication, making it harder for bad actors to impersonate your brand and improving deliverability for legitimate messages.

Email sender hygiene used to be about clean lists and avoiding spammy content. Today, it's also about technical integrity. Here’s what that looks like:

• All outbound mail activity authenticates successfully with SPF, DKIM, and DMARC.
• DMARC reports are regularly monitored to identify unauthorised senders and mitigate deliverability issues.
• Use a consistent “From” address aligned with your domain.
• Keep DNS records and email headers up-to-date with modern standards.

If you’re not maintaining your email reputation, you’re putting your brand reputation and deliverability at risk.

Email authentication is no longer just good practice—it’s a necessity. Whether you're sending newsletters, invoices, or support replies, your domain must be properly authenticated to ensure your message is seen and trusted.

If you're unsure where to start, Serversaurus offers a comprehensive Email Analysis and Security consultation, which guides you through implementing SPF, DKIM and DMARC policies to ensure your sender reputation is protected.