Laposte.net tightens its requirements for email authentication

On Friday, August 22, in a message shared by Simon Bressier, Postmaster of Laposte.net, the mail provider announced a major shift in its deliverability and anti-spam policy starting in September 2025. The French webmail confirmed that email authentication standards (SPF, DKIM, and DMARC) will no longer be optional.

Until now, some emails without authentication protocols could still reach users’ inboxes. But this is about to change:

Starting in September, 100% of emails without SPF, DKIM, or DMARC will be redirected to the spam folder at best.

Why this change?

This move is part of a global trend in the email industry. Authentication has become a mandatory requirement to:

• Strengthen user security by reducing the risks of phishing and spoofing. 
• Increase trust in legitimate senders by ensuring their messages are correctly identified.
  

Help ISPs and webmail providers manage traffic, as they must process ever-growing volumes of email.

What are Laposte.net’s expectations?

Simon Bressier emphasizes that Laposte.net now expects senders to properly authenticate and protect their domains:

• SPF (Sender Policy Framework): defines which servers are authorized to send emails for a given domain.
• DKIM (DomainKeys Identified Mail): adds a cryptographic signature to each message, ensuring it hasn’t been altered between the sending and receiving servers.
• DMARC (Domain-based Message Authentication, Reporting & Conformance): tells receiving servers how to handle emails that fail SPF/DKIM checks, and provides reporting for monitoring.
  

These mechanisms, recommended for years, are now mandatory to ensure good deliverability on Laposte.net.

What’s next?

The Postmaster of Laposte.net indicated that further announcements will be made soon to outline the next steps. It is likely that the platform will continue to strengthen its requirements in the near future, following the path already taken by Google and Yahoo since February 2024.

What should senders do?

If not already in place, organizations must:

1. Implement SPF and DKIM on all sending domains. 
2. Deploy an appropriate DMARC policy (starting with p=none, then moving to quarantine or reject). 
3. Monitor DMARC reports to detect any anomalies. 
4. Verify consistency across all domains, including secondary or unused ones.

Conclusion

With this announcement, Laposte.net confirms that email authentication is no longer optional but mandatory. Senders who fail to comply will see their emails relegated to spam at best, or rejected altogether — severely impacting deliverability.

This stricter stance aligns with the global shift where security and trust are becoming the cornerstones of the email ecosystem.