As of May 5, 2025, Microsoft has begun enforcing DMARC, SPF, and DKIM for high-volume email senders. This is not a suggestion – it’s a requirement. Businesses that fail to comply risk having their emails rejected or marked as spam, potentially harming communication, reputation, and revenue.
At Avantguard, we’ve already implemented these protocols across all our client domains, ensuring they remain secure, compliant, and ahead of the curve. We use DMARCReports, a trusted platform (comparable to Sendmarc) that helps us monitor and manage domain security.
If you’re not a current Avantguard client, this blog post is for you. We’ll explain:
- What these standards mean
- Why DMARCReports matters
- The broader business impact
- How we can help you stay protected — and connected
📬 What Are DMARC, SPF & DKIM?
These are email authentication protocols designed to verify that the sender of an email is legitimate and authorized
🔐 SPF – Sender Policy Framework
Checks whether an email comes from an IP address authorized to send emails on behalf of a domain. It helps prevent spammers from sending messages that appear to come from your domain.
✍️ DKIM – DomainKeys Identified Mail
Adds a digital signature to your emails that verifies they haven’t been altered during transmission and confirms they were actually sent from your domain.
✅ DMARC – Domain-based Message Authentication, Reporting & Conformance
The orchestrator of email security. DMARC uses SPF and DKIM results to decide what to do with an unauthenticated email. It also sends reports to the domain owner detailing how many emails passed or failed.
📊 What Is DMARCReports?
DMARCReports is a cloud-based email security platform that provides detailed visibility into how your domain is being used — or misused. It analyzes DMARC reports and turns complex data into actionable insights.
Key Features:
- Daily and weekly summaries of authentication success/failure
- Alerts when someone tries to spoof your domain
- Visualization tools to help understand your email flow
- Recommendations to fix misconfigurations
- Historical data for tracking trends
DMARCReports provides a proactive approach to security, not just a reactive one.
DMARC Authentication Overview:
For an email message to pass DMARC (Domain-based Message Authentication, Reporting & Conformance) authentication, it must either:
- Pass SPF (Sender Policy Framework) authentication and SPF alignment, or
- Pass DKIM (DomainKeys Identified Mail) authentication and DKIM alignment.
If a message fails DMARC, the sender’s domain specifies how receivers should handle it through a DMARC policy. The three possible policies are:
- None: The message is delivered normally, but DMARC reports are sent to the domain owner.
- Quarantine: The message is marked as suspicious and typically sent to the recipient’s spam or junk folder.
- Reject: The message is outright blocked and not delivered.
Organizations are advised to begin with a “none” policy to collect DMARC reports and identify all legitimate email sources. Within 12 months, they should aim to transition to a stricter policy. Once all valid senders are authenticated and any issues are resolved, moving to a “reject” policy enables the domain to effectively block phishing, business email compromise (BEC), and other malicious email threats.
Email-receiving organizations should configure their secure email gateways to enforce the DMARC policies set by domain owners. This helps protect users from inbound threats and supports the broader email security ecosystem.
🔍 Why Is DMARC Important?
Without proper DMARC enforcement, anyone can impersonate your domain, leading to:
- Phishing attacks that trick customers or partners
- Brand damage and lost trust
- Legal and compliance risks
- Emails going to spam, even if they’re legitimate
By enforcing DMARC (along with SPF and DKIM), you’re telling email providers: “Only emails sent from these verified sources should be trusted.”
📊 The Rising Threat Landscape
Email-based threats have escalated dramatically in recent years:
- 150% Increase: Phishing attacks have surged by 150% since 2019.
- 84% Growth: Valid DMARC policies grew by 84% in 2021, reflecting a global push towards better email security.
- 2x Brand Spoofing: The number of brand names spoofed in phishing attacks has nearly doubled in recent years.
These statistics underscore the critical need for robust email authentication measures.
🚀 Benefits of DMARC for Sales & Marketing
1. Improved Email Deliverability
Marketing and sales emails only work if they’re seen. DMARC helps ensure that your emails land in inboxes, not junk folders.
2. Stronger Brand Reputation
When prospects see emails from your domain, they trust it’s really from you. DMARC protects against brand spoofing, which can destroy credibility overnight.
3. Better Engagement Rates
Emails that land in spam folders don’t get opened. With improved trust and deliverability, you’ll see higher open rates, click-throughs, and conversions.
4. Data-Driven Optimization
With DMARCReports, you can monitor your campaigns and know:
- Which mail servers are being used
- Where failures are happening
- Whether any third-party platforms (e.g., Mailchimp, HubSpot) are misconfigured
5. Competitive Edge
A properly authenticated email system reflects professionalism and operational maturity. You’re more likely to win business when customers know their data and communications are secure.
✅ Avantguard Customers Are Already Covered
We’ve taken a proactive approach and set up DMARC, SPF, and DKIM for all Avantguard customers — using DMARCReports for ongoing monitoring and reporting.
What does that mean for our clients?
- No action required
- Full compliance with Microsoft’s requirements
- Ongoing visibility and protection
- Peace of mind
📄 Sample Advanced DMARC Aggregate Report
Domain Monitored: example.com
Date Range: May 1, 2025 – May 7, 2025
Policy: p=reject; rua=mailto:dmarc@example.com
Summary Dashboard
| Metric | Value |
| Total Emails Processed | 125,000 |
| Emails Passed DMARC | 119,400 (95.5%) |
| Emails Failed DMARC | 5,600 (4.5%) |
| SPF Pass | 121,800 (97.4%) |
| DKIM Pass | 116,300 (93.0%) |
| Spoofed Sources Identified | 3 |
| Third-Party Senders Flagged | 5 |
📈 Daily Email Authentication Overview
| Date | Total Emails | DMARC Pass | DMARC Fail | SPF Pass | DKIM Pass |
| 2025-05-01 | 18,300 | 17,420 | 880 | 17,940 | 17,000 |
| 2025-05-02 | 17,500 | 16,820 | 680 | 17,100 | 16,600 |
| 2025-05-03 | 17,100 | 16,500 | 600 | 16,800 | 16,200 |
| 2025-05-04 | 18,700 | 17,850 | 850 | 18,200 | 17,600 |
| 2025-05-05 | 19,800 | 18,900 | 900 | 19,400 | 18,600 |
| 2025-05-06 | 17,300 | 16,600 | 700 | 17,000 | 16,400 |
| 2025-05-07 | 16,300 | 15,310 | 990 | 15,800 | 14,900 |
🚨 Authentication Failures by Source
| Source IP | Hostname | Reverse DNS | SPF | DKIM | DMARC | Volume | Action |
| 194.12.11.77 | unknown | n/a | Fail | Fail | Fail | 1,200 | Rejected |
| 185.26.230.99 | smtp.mailtrap.io | mailtrap.io | Pass | Fail | Fail | 850 | Quarantined |
| 35.190.247.1 | sendgrid.net | sg2.sendgrid.net | Pass | Pass | Pass | 13,000 | Delivered |
💡 Insights & Recommendations
✅ Trusted Sources
- Google Workspace
- Microsoft 365
- SendGrid
❌ Suspicious Senders
- 194.12.11.77 – unknown source, possibly spoofing attempts. Add this to your blocklist.
- mailtrap.io – DKIM not aligned. Confirm it’s authorized to send on your behalf.
📌 Actionable Steps
- Align DKIM on mailtrap.io testing environment or switch to trusted sandbox tools.
- Strengthen subdomain policies (sp=reject) to prevent spoofing on variants.
- Review and document all third-party services that send email on behalf of example.com.
Here is the sample 📉 DMARC Pass vs Fail trend graph for the 7-day period. It visually illustrates the volume of emails that passed and failed DMARC authentication each day.
🧭 Not an Avantguard Client Yet? Here’s How We Can Help
If you’re not yet working with us, now’s the time to ensure you’re compliant. Microsoft isn’t the only major provider tightening security — Gmail, Yahoo, and others are doing the same.
We offer:
- Domain authentication audits
- Complete setup of SPF, DKIM, and DMARC
- Integration with DMARCReports for ongoing visibility
- Monthly monitoring and adjustments as needed
- Training and documentation for your IT team
🧠 Final Thoughts
Microsoft’s new enforcement of email authentication is a wake-up call for any business relying on digital communication. Whether you’re in marketing, sales, operations, or leadership, ensuring your domain is protected is no longer optional — it’s essential.
At Avantguard, we’ve got the tools, experience, and foresight to keep your business safe and thriving in today’s email landscape.
