How will LaPoste.net's new email authentication requirements affect your deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 5 Jun 2025
Updated 11 Sep 2025
9 min read
Starting on September 9th, at 9 AM French time, LaPoste.net will implement strict penalties for emails that lack valid authentication via SPF, DKIM, or DMARC. This is a significant shift that email senders, especially those targeting French recipients, need to be aware of. The consequences for non-compliance are severe, ranging from emails being placed directly into the spam folder to outright rejection. These changes reflect a growing trend among major mailbox providers to enhance email security and combat phishing and spoofing attempts.
This move by LaPoste.net echoes the recent policy updates from large providers like Gmail and Yahoo, signaling a global push for stronger email authentication standards. It is no longer enough to merely have SPF and DKIM records, they must also be correctly aligned with your RFC5322.From header. Failing to meet these new alignment requirements means your authentication will be treated as if it doesn't exist at all, leading to significant deliverability challenges.
Understanding LaPoste.net's new authentication rules
The core of LaPoste.net's new policy revolves around the alignment of your email authentication protocols (SPF and DKIM) with your sending domain. Previously, some emails might have slipped through without perfect alignment, but those days are over. Now, SPF and DKIM are considered 'none' if they are not aligned with the RFC5322.From domain. This is a critical distinction, as having a record that doesn't align is as bad as having no record at all in the eyes of LaPoste.net.
SPF alignment: If the MailFrom (RFC5321) domain does not align with your Header From, SPF will be considered 'none'.
DKIM alignment: If the domain signed by DKIM does not align with your Header From, DKIM will also be considered 'none'.
Shared domains: Email Service Providers (ESPs) often use shared domains for MailFrom or DKIM signatures. If these shared domains are not aligned with your brand's Header From domain, they will be treated as non-aligned. This means you must ensure at least one DKIM signature provided by your ESP or a custom one, aligns.
Multiple DKIM signatures: If your email carries multiple DKIM signatures, only one needs to pass and align for the email to be considered authenticated by LaPoste.net.
These technical points highlight the need for a precise configuration of your DNS records. It is no longer enough to just have records, they need to correctly reflect your sending domain to ensure successful delivery.
Why are these changes happening?
LaPoste.net's decision to tighten its email authentication requirements is a direct response to a surge in phishing attempts and email spoofing. Like other major mailbox providers (such as Gmail and Yahoo), they are prioritizing user protection by ensuring that emails received are genuinely from the stated sender. Unauthenticated or misaligned emails are prime indicators of potentially malicious activity.
By enforcing stricter authentication policies, LaPoste.net aims to filter out fraudulent emails before they reach inboxes, thereby safeguarding their users from scams and identity theft. This benefits not only the recipients but also legitimate senders, as a more secure email ecosystem reduces the overall risk of your emails being caught in broader spam filters. These efforts are part of a larger industry movement towards a more secure and trustworthy email environment.
This proactive stance on email security helps everyone. For businesses and individuals, it means that the emails they send are more likely to be trusted and delivered. For recipients, it translates to fewer spam and phishing messages, improving their overall email experience. It is a necessary step in the ongoing fight against email-based cyber threats, and all senders should embrace these changes as a standard practice.
Impact on your email deliverability
The most immediate and critical impact of these new requirements will be on your email deliverability. If your emails fail to meet LaPoste.net's authentication and alignment standards, they will face severe consequences. At best, they will be relegated to the spam folder, making it unlikely for your recipients to ever see them. In many cases, non-compliant emails will be rejected outright, meaning they won't even reach the spam folder.
Before September 9th
Under the previous, more lenient rules, emails without perfect SPF, DKIM, or DMARC alignment might still reach the inbox. This created a loophole for spammers and phishers to exploit, making it harder for users to distinguish legitimate emails from malicious ones. Mailbox providers often relied on a broader set of signals for inbox placement.
Risk: Higher chance of spoofing and phishing attacks for users.
Sender effort: Less stringent requirements, some senders may not have fully optimized authentication.
After September 9th
With the new stringent requirements, email authentication and alignment are mandatory for all senders. Emails that fail to meet these standards will face immediate penalties, severely impacting their deliverability. This significantly reduces the window for bad actors to impersonate legitimate senders.
Deliverability: Non-compliant emails will be sent to spam or rejected. Requires action.
User safety: Enhanced protection against phishing and domain spoofing.
This means that even if you have an SPF record and a DKIM signature, if they are not correctly aligned with your Header From domain, LaPoste.net will effectively ignore them. This can severely damage your sender reputation and negatively impact your overall email deliverability rates, leading to lost engagement and potential business impact. It's crucial to understand that merely having the records is insufficient; they must be correctly implemented for authentication to pass.
For ESPs using shared domains, this presents a particular challenge. While the SPF MailFrom domain (RFC5321) might be shared across all ESP users, it will not align with your specific Header From domain (RFC5322.From). In such cases, a valid and aligned DKIM signature becomes even more critical. If your ESP does not provide an aligned DKIM, you will need to implement a custom DKIM signature for your domain.
Ensuring compliance and maintaining good deliverability
To navigate these new requirements effectively, a thorough review of your current email authentication setup is essential. This proactive approach will help ensure your emails continue to reach LaPoste.net inboxes without issue. Here are the key steps you should take immediately:
Verify SPF and DKIM alignment: Ensure your SPF MailFrom domain and your DKIM signing domain align with your RFC5322.From header. If you use an ESP, confirm they provide aligned authentication or configure it yourself.
Implement DMARC: DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds upon SPF and DKIM to provide policy and reporting. It's the most robust way to protect your domain and ensure deliverability. Start with a p=none policy to monitor compliance without impacting delivery.
Monitor DMARC reports with Suped:Suped offers the best DMARC reporting and monitoring tool on the market, with a very generous free plan. Utilize a DMARC monitoring tool to gain visibility into your email streams and identify authentication failures. This will show you exactly which emails are failing and why, allowing you to quickly make corrections.
Test your deliverability: Before the deadline, send test emails to LaPoste.net addresses and monitor their inbox placement. This will give you real-world insights into your compliance status. Utilize an email deliverability test to catch any issues.
Example: DKIM Alignment for shared domains
If your Header From is yourdomain.com, and your ESP uses a shared MailFrom of esp.com, SPF will not align. You then need to ensure a DKIM signature with a signing domain of yourdomain.com is present and valid. If the only DKIM signature is also from esp.com, your email will fail authentication.
DNS Record Example (Aligned DKIM)TXT
yourselector._domainkey.yourdomain.com. IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDyX6dY..."
It's worth noting that these requirements for LaPoste.net are just the first step. The provider has indicated that more changes are to come in the near future, suggesting a continued evolution towards stricter email security protocols. Therefore, establishing a robust and compliant email infrastructure now is not just about meeting current requirements, but also about preparing for future demands and maintaining long-term email deliverability and sender reputation.
Views from the trenches
Best practices
Always prioritize DMARC implementation and monitoring to gain full visibility over your email channels.
Ensure that all sending platforms, especially ESPs, are configured for DMARC-compliant SPF and DKIM alignment.
Regularly check your DMARC reports for authentication failures and address them promptly to maintain domain reputation.
Educate your team on email authentication best practices to prevent inadvertent configuration errors.
Common pitfalls
Assuming SPF and DKIM are sufficient without checking for alignment with the Header From domain.
Not monitoring DMARC reports, leading to undetected authentication failures and deliverability issues.
Relying solely on ESPs for authentication without verifying their DMARC compliance for your specific domain.
Ignoring shared domain challenges, which can cause SPF to fail alignment, requiring DKIM to compensate.
Expert tips
Use Suped to visualize your DMARC reports, quickly identifying sources of failure and opportunities for improvement.
For shared domains, focus on strong DKIM alignment. It is often the easiest path to DMARC compliance.
Stay informed about postmaster updates from major mailbox providers to anticipate future requirements.
Consider implementing BIMI once DMARC is at p=quarantine or p=reject to enhance brand trust and visibility.
Expert view
Expert from Email Geeks says that LaPoste.net's move to tighten authentication, requiring SPF or DKIM to pass and align with RFC5322.From, is a smart decision to combat phishing.
September 4, 2025 - Email Geeks
Expert view
Expert from Email Geeks says that if an ESP uses a shared SPF domain that doesn't align, a valid and aligned DKIM signature is absolutely necessary for compliance.
September 4, 2025 - Email Geeks
Key takeaways for senders
LaPoste.net's new email authentication requirements mark a pivotal moment for senders targeting French inboxes. The emphasis on SPF and DKIM alignment, alongside the penalties for non-compliance, underscores the critical need for robust email security practices. Ignoring these changes risks your emails being rejected or sent to spam, severely impacting your communication effectiveness and sender reputation.
By actively reviewing and updating your email authentication configurations and leveraging DMARC monitoring with Suped, you can ensure your emails remain compliant and reach their intended recipients. These steps are not just about avoiding penalties, they are about building trust with mailbox providers and recipients, ultimately leading to better email deliverability and engagement.
The email landscape continues to evolve towards higher security standards. Adapting to these changes proactively will not only safeguard your email program today but also position you for continued success in the future. Embrace these updates as an opportunity to strengthen your email infrastructure and enhance your overall email deliverability.
