Why are French ISPs like Orange and SFR particularly strict with email filtering?

French ISPs, like Orange and SFR, are known for their strict email filtering policies, often employing advanced anti-spam solutions like Vade Secure. They prioritize user protection against spam and phishing, which means any activity that raises red flags—such as high spam complaints, sending to old lists, or sudden volume spikes—can quickly lead to blocks or bounces.

How do I access the raw SMTP bounce messages from my Email Service Provider (ESP)?

Accessing raw bounce messages depends on your Email Service Provider (ESP). You typically find them within your sending platform's bounce logs or activity feeds, often in a "raw JSON" or "technical details" section for each bounced email. If you can't locate them, contact your ESP's support and specifically request the full SMTP reply messages.

What role does Vade Secure play in email filtering for French ISPs?

Vade Secure is a widely used anti-spam and email security provider in France. Many French ISPs, including Orange, SFR, and La Poste, integrate Vade's filtering technology. This means that if your emails trigger Vade's filters due to reputation or content issues, you're likely to experience bounces or blocks across multiple French domains simultaneously.

Can shared IP addresses cause bounce spikes on French ISPs?

Yes, using shared IPs can contribute to bounce spikes on French ISPs. If other senders on the same shared IP engage in problematic sending practices (e.g., sending spam, hitting spam traps), the overall reputation of that IP can suffer. ISPs may then block or throttle all mail from that IP, impacting your legitimate emails, even if your own sending practices are good.

How often should I monitor my sending reputation for French ISPs?

You should monitor your sending reputation continuously, especially if you send to French ISPs. Daily checks of your bounce rates and any specific SMTP error codes are advisable. For long-term insights, regularly review your DMARC reports and any postmaster tools provided by ISPs, which can highlight recurring patterns or reputation trends.

What causes bounce spikes on French ISPs like Orange, SFR & La Poste, and how can I troubleshoot them? - Troubleshooting - Email deliverability - Knowledge base

Dealing with sudden email bounce spikes, especially from major French Internet Service Providers (ISPs) like Orange, SFR, and La Poste, can be incredibly frustrating. It often feels like hitting a brick wall, particularly when it's not simply a list quality issue but something more nuanced with the ISP itself. We've seen this challenge repeatedly, often with periodic spikes every couple of weeks, even when sending from shared IPs.

The common assumption might be that your email list is stale or contains too many invalid addresses. While list hygiene is always crucial for email deliverability, the nature of these sudden, widespread spikes across multiple French ISPs often points to deeper filtering mechanisms at play, beyond what a simple list cleaning can fix. This is particularly true when using shared IP addresses, where the reputation of other senders can impact your own.

The challenge intensifies when bounce messages are vague, often classified simply as "unclassified" by email service providers (ESPs). This lack of specific detail makes pinpointing the exact cause and formulating a solution much more difficult, requiring a deeper dive into the technicalities of email delivery. Understanding the underlying reasons is key to restoring your email flow and ensuring your messages reach the intended recipients.

Understanding French ISP filtering

French ISPs, like many large email providers, employ sophisticated spam filtering systems to protect their users. These systems are constantly evolving and can be particularly sensitive to sudden changes in sending patterns, content, or sender reputation. Orange, SFR, and La Poste (usually through the Orange network) are known for their stringent rules.

One significant factor influencing email deliverability to French ISPs is the widespread use of filtering technology like

Vade Secure. This anti-spam and email security provider is widely adopted by many French ISPs, meaning that if you trigger Vade's filters, you're likely to see bounces across multiple domains, not just one. Vade's system analyzes various signals, including sender reputation, content, and sending behavior, to determine whether an email should be delivered or blocked. They even offer a sender tool for some insights, though ESPs typically manage interactions with it.

Beyond specific filtering technologies, these ISPs also maintain their own internal blocklists (or blacklists) based on real-time data from their users. Factors like spam complaints, low engagement, and sending to invalid email addresses (spam traps) can quickly land your sending IP or domain on these internal blocklists, leading to those frustrating bounce spikes. Each ISP has its own thresholds and algorithms, which makes a unified approach to troubleshooting essential.

Understanding how various factors impact email deliverability to French ISPs is crucial. Here's a summary:

Factor	Impact on French ISPs
Sender reputation	Highly weighted. Poor reputation (due to complaints, spam traps, or shared IP issues) leads to aggressive filtering and bounce spikes. Google Postmaster Tools can provide a general overview, but specific ISP feedback is needed.
Content quality	Spammy keywords, broken links, or overly promotional material can trigger filters, especially those from Vade Secure, resulting in bounces.
Email authentication	Proper SPF, DKIM, and DMARC records are essential. Missing or misconfigured records can lead to emails being rejected, particularly by ISPs with strict security policies.
List hygiene	Even if not the primary cause of spikes, sending to invalid addresses or spam traps significantly damages reputation and can lead to immediate blocklisting (or blacklisting). SFR, for instance, is known to return GU_EIB_02 SMTP codes for list hygiene issues.

Decoding bounce messages

One of the most crucial steps in troubleshooting bounce spikes is getting past the generic classifications provided by your ESP. While an ESP might categorize a bounce as "soft bounce" or "unclassified," the real insights lie in the raw SMTP reply message from the receiving server. These messages often contain specific error codes or human-readable text that can tell you exactly why an email was rejected.

The importance of raw SMTP replies

When an email is rejected, the recipient's mail server sends back an SMTP (Simple Mail Transfer Protocol) reply. This reply contains a numeric code (e.g., 550, 421) and often a text string explaining the reason for the rejection. Many ESPs simplify these messages for reporting purposes, which can obscure the actual problem. For example, Orange.fr might send OFR_999 errors indicating temporary throttling, which your ESP might simply label as a soft bounce.

How to find them

Accessing these raw SMTP replies depends entirely on your ESP. You'll often find them within your sending platform's bounce logs or activity feeds, usually under a raw JSON or technical details section associated with each bounced email. If you're struggling to locate them, reach out to your ESP's support team and specifically ask for the full, unedited SMTP bounce replies. Remember that some platforms may only retain these logs for a limited period, such as 14 days.

Interpreting the codes

Once you have the raw SMTP codes, you can interpret their meaning. Many are standard, but some ISPs have proprietary codes. Resources like the SMTP Field Manual can be incredibly helpful for deciphering general codes and common ISP responses. This step is critical because without knowing the exact reason for the bounce, you're essentially guessing at a solution, which can prolong the issue and further damage your sender reputation.

For example, a common raw bounce message from Orange.fr might look something like this:

Example SMTP bounce messageplain

550 5.7.1 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked using bl.spamcop.net; see https://www.spamcop.net/bl.shtml?xxx.xxx.xxx.xxx

This specific message indicates that your sending IP address (xxx.xxx.xxx.xxx) is listed on the SpamCop blocklist (or blacklist), leading to a hard bounce. This is far more informative than a generic "unclassified bounce" and directly points to a reputation issue that needs addressing.

Common causes of bounce spikes

Bounce spikes on French ISPs can stem from several common issues. While you mentioned it's not a direct list quality issue, these factors often interlink and contribute to filtering problems:

Reputation hits: Even on shared IPs, your domain's reputation is critical. If your domain or the shared IP experiences a sudden increase in spam complaints, hits a spam trap, or is associated with suspicious sending patterns, ISPs like Orange, SFR, and La Poste may temporarily block your mail.
Volume changes: A sudden, large increase in sending volume, especially to previously unengaged recipients, can be flagged as anomalous. This is a common trigger for ISP throttling or temporary blocks.
Content issues: Even if your list is good, spammy content, excessive links, or poorly formatted HTML can trigger content-based filters, especially those used by Vade Secure and other French filtering systems. This can lead to a sudden increase in bounces or emails landing in the spam folder.
Authentication failures: Issues with SPF, DKIM, or DMARC can lead to emails being rejected outright. ISPs are increasingly strict about proper email authentication as a measure against phishing and spoofing. Ensure your DMARC record is correctly configured and aligned.
Network issues or outages: While less common, sometimes ISP-side network issues can cause temporary bounce spikes. For instance, SFR has experienced outages that impact all their services, including email. These are usually short-lived but can significantly impact your sending metrics temporarily. In such cases, your ESP should be aware and communicate with you.

It's essential to look at your bounce data holistically and not just rely on generic categories. The periodic nature (every 2 weeks) suggests that your sending patterns might be hitting a recurring reputation threshold or a scheduled review process at the ISPs.

Strategies for troubleshooting and prevention

Troubleshooting bounce spikes, especially on French ISPs, requires a methodical approach. The goal is to identify the root cause by gathering specific data and then implementing targeted solutions.

Reactive troubleshooting

Collect raw bounce data: As discussed, this is your primary diagnostic tool. Get the full SMTP replies from your ESP for every bounce from Orange, SFR, and La Poste. Look for specific error codes like OFR_999 for Orange or specific Vade Secure messages. This helps categorize the actual bounce reason, moving beyond temporary bounces.
Check your blocklist status:Verify if your sending IP or domain is listed on any public blocklists (blacklists), especially those frequently used by European ISPs. While French ISPs primarily use internal lists or Vade, getting listed on public ones will also cause issues.
Analyze sending patterns: Review your sending volume and frequency leading up to the spikes. Were there any unusual campaigns or increases in volume? This can trigger temporary blocks or sudden email bounce rate spikes.

Once you have gathered the necessary data and identified potential causes, you can implement preventative measures to improve your email deliverability to French ISPs.

Prevention strategy: proactive measures

Maintain high sender reputation: Focus on consistent sending practices, monitor engagement, and keep spam complaint rates low. This is the cornerstone of good deliverability and helps prevent your IP or domain from getting on an email blacklist (or blocklist).
Segment and warm up lists: If you're sending to new or less engaged segments, warm them up gradually. Avoid sudden, large sends to inactive subscribers, which can trigger spam filters and lead to high bounce rates during IP warming.
Regularly clean your lists: Even if not the primary cause of your current spikes, removing inactive or invalid email addresses prevents future issues and improves overall list health.

Prevention strategy: technical setup

Strengthen authentication: Ensure your SPF, DKIM, and DMARC records are correctly set up and aligned. This validates your emails and builds trust with ISPs. Regularly monitor your DMARC monitoring to catch any authentication failures.
Optimize content: Review your email content for anything that might trigger spam filters. Use clear, concise language, avoid excessive images, and ensure all links are legitimate. A well-designed email is less likely to be flagged.
Engage with postmasters: If the issue persists and you have specific bounce codes, try to engage with the postmaster teams at Orange, SFR, or La Poste directly. They can sometimes provide more granular feedback or whitelist your sending IP if your practices are legitimate.

Views from the trenches

Best practices

Always prioritize collecting raw SMTP bounce messages for detailed diagnostics, as generic ESP classifications are often insufficient.

Implement and maintain robust email authentication, including SPF, DKIM, and DMARC, to build trust with ISPs.

Monitor your sending volume and frequency, adjusting to gradual increases to avoid triggering ISP throttling mechanisms.

Common pitfalls

Relying solely on your ESP's bounce categorization, which often masks the true reason for email rejections.

Ignoring periodic bounce spikes, as they can indicate recurring reputation issues or evolving ISP filtering rules.

Failing to adapt email content to avoid triggering common spam filters, especially those like Vade Secure.

Expert tips

Proactively check your sending IP and domain against major blocklists, even if your ESP reports no issues.

Utilize engagement data to segment your audience and send more targeted, relevant emails that reduce complaint rates.

Establish a feedback loop with relevant ISPs to receive direct reports on spam complaints and maintain a clean sending reputation.

Marketer view

Marketer from Email Geeks says it's important to clarify the exact nature of bounce messages, as specific codes provide crucial diagnostic information.

2024-04-02 - Email Geeks

Expert view

Expert from Email Geeks says that when multiple French ISPs show bounce spikes simultaneously, it often indicates a common underlying filtering system, such as Vade Secure.

2024-04-02 - Email Geeks

Resolving deliverability challenges

Navigating bounce spikes with French ISPs like Orange, SFR, and La Poste requires persistence and a deep understanding of email deliverability best practices. The key takeaway is to move beyond superficial bounce classifications and delve into the raw SMTP replies for actionable insights. This granular data will tell you if the issue is reputation-based, content-related, or due to authentication failures.

By proactively monitoring your sender reputation, ensuring proper email authentication (SPF, DKIM, DMARC), and engaging in consistent list hygiene, you can mitigate many of the common causes of these spikes. While shared IPs can introduce complexities, focusing on these fundamental aspects of email security will significantly improve your chances of consistently reaching the inbox. Remember, successful email delivery to French ISPs often hinges on building and maintaining a strong, trustworthy sender profile.