What causes unclassified soft bounces from Orange.fr in Klaviyo, and how can they be resolved?
Michael Ko
Co-founder & CEO, Suped
Published 13 Aug 2025
Updated 17 Aug 2025
8 min read
Encountering unclassified soft bounces from Orange.fr when sending emails through Klaviyo can be a frustrating experience. Unlike a hard bounce, which indicates a permanent delivery failure, a soft bounce is typically temporary, often due to a full inbox or a server issue. However, when these bounces are unclassified, it means the email service provider (ESP) like Klaviyo cannot immediately pinpoint the exact reason for the bounce. This lack of specific information makes troubleshooting particularly challenging, leaving you without clear actionable insights.
Many email marketers commonly encounter soft bounces for reasons such as a recipient's inbox being full or the server being temporarily unavailable. Soft bounces are typically temporary, allowing ESPs to retry sending the email later. However, when these attempts fail persistently and the bounce remains unclassified, especially from a specific internet service provider (ISP) like Orange.fr, it often signals a deeper underlying issue than a simple temporary problem.
This article delves into the common causes behind these elusive unclassified soft bounces from Orange.fr within your Klaviyo account and outlines actionable strategies to diagnose and resolve them effectively. Understanding the true nature of these bounces is crucial for maintaining your email deliverability and ensuring your messages reach their intended recipients.
Unclassified soft bounces from Orange.fr
When Klaviyo reports an unclassified soft bounce, it essentially means the returned error message from the recipient server does not fit into Klaviyo's predefined bounce categories. This can occur for several reasons, such as new or obscure error codes, or insufficient detail in the bounce message itself. The key to solving this puzzle often lies in getting access to the actual SMTP (Simple Mail Transfer Protocol) bounce message from Klaviyo's logs. Your ESP should be able to provide this, as it contains the precise error communication from the receiving server.
What an unclassified soft bounce means
An unclassified soft bounce happens when an email server returns an error that your ESP cannot readily categorize. This means it is either a new type of bounce reason, or the provided information is too generic or incomplete for automatic classification. It's crucial to understand that the classification often reflects the ESP's interpretation, rather than the raw, unfiltered error from the recipient server. Always request the raw bounce message from your ESP to get the full picture.
In the case of Orange.fr, you might observe a specific bounce message indicating a greeting failed alongside an OFR_999 error code. This particular error provides a significant clue. It means your mail transfer agent (MTA) successfully connected to the Orange.fr mail exchange (MX) server, but the initial SMTP conversation, specifically the HELO or EHLO greeting, was rejected. This happens even before your email content, sender, or subject line are evaluated.
Root causes of Orange.fr connection failures
The OFR_999 error from Orange.fr (or other 99X codes) indicates a temporary block due to what Orange perceives as bad behavior, often related to the sending IP's reputation or connection patterns. This is a common issue with French ISPs which are known for their strict email filtering policies. If you are on a shared IP address within Klaviyo, the problem could stem from the sending behavior of other users on that same IP. It is not necessarily related to your specific campaign content or email template, despite what basic support might suggest.
Example Orange.fr bounce message
Connected to 80.12.26.32 but greeting failed
Remote host said: 421 opmta1mti03nd1 smtp.orange.fr KW7staye8WwuK Service refuse. Veuillez essayer plus tard. Service refused, please try later. OFR_999 [999]
I'm not going to try again; this message has been in the queue too long.
This 421 error, combined with greeting failed, points to issues occurring at the very beginning of the SMTP handshake. This could be due to your sending IP (or Klaviyo's shared IP) being on a blacklist (or blocklist), or Orange.fr rate-limiting too many simultaneous connections from that IP. Orange's Postmaster site confirms that 99X error codes are linked to bad behavior leading to rate limiting or even temporary suspension of the IP.
It is critical to distinguish this from content-related issues. Since the connection itself is failing, the problem arises before the email content is even scanned for keywords like FREE. Therefore, changing your email template or content is unlikely to resolve OFR_999 bounces. The focus should be on the IP reputation and connection parameters. Understanding this distinction is key to effectively addressing the issue with your ESP, as it shifts the troubleshooting from content to infrastructure.
Orange.fr Error Code
Meaning
Likely Cause
OFR_999 (421 Service Refused)
Due to bad behavior, you have been rate limited; please try again later.
IP reputation issue, excessive connections, or previous spam complaints.
OFR_xxx (451 Transient Failure)
Temporary failure; recipient's server issues or greylisting.
Temporary server overload or standard greylisting policies applied by Orange.fr.
Strategic steps for resolution in Klaviyo
To resolve these unclassified soft bounces, especially those with the OFR_999 code, your primary course of action involves a detailed conversation with Klaviyo's support team. Insist on obtaining the full, raw SMTP bounce message, as this is the only way to get the precise error details from Orange.fr. Once you have this, you can clearly articulate that the failure occurs at the connection (greeting) stage, indicating an IP-based problem rather than a content-based one. This evidence helps steer the support conversation towards the correct technical diagnosis and resolution.
Understanding responsibilities
Your Responsibility: Focus on list hygiene, sending engaged emails, and ensuring proper email authentication (SPF, DKIM, DMARC) for your sending domain.
ESP Responsibility: Klaviyo is responsible for managing the reputation of their sending IPs, adjusting connection rates to ISPs like Orange.fr, and resolving IP-based blocklist issues. They should escalate the issue internally if initial support cannot resolve it.
Since you are on a shared IP with Klaviyo, direct contact with Orange.fr postmaster is not the most effective first step. As a user of a shared IP, you lack the direct control or oversight over the entire sending volume and reputation of that IP. It is Klaviyo's responsibility to manage their shared IP pools and ensure they comply with ISP policies, including Orange.fr'stightening deliverability standards. If this issue persists, it may indicate a broader problem with the shared IP's reputation or Klaviyo's overall sending practices on that particular IP.
Resolving orange.fr bounces in Klaviyo
When communicating with Klaviyo, arm yourself with the bounce message, clearly stating that the issue is at the connection stage (a greeting failure) and includes an OFR_999 code. Explain that this points to an IP-based block or rate limit from Orange.fr, which is a problem for Klaviyo to resolve. Provide links to Orange's postmaster documentation on these error codes to support your claim. This direct and technically informed approach is more likely to get the issue escalated to a senior deliverability specialist who can address the root cause, rather than suggesting irrelevant content changes.
Ensure your sending domain is properly configured with your own DKIM authentication, even if you are on a shared IP. This gives you more control over your domain's reputation, separate from the shared IP. For Klaviyo users, enabling branded sending domains and dedicated click tracking is a crucial step to improve deliverability, as detailed in some deliverability guides. This helps insulate your sending reputation from the potential issues of other senders on a shared IP.
Best practices for engaging your ESP
Gather Data: Always ask for the raw bounce messages, including the SMTP error codes and diagnostic text.
Be Specific: Clearly state that the issue is a connection failure (e.g., greeting failed), not a content or recipient problem.
Refer to ISP Policies: Cite specific postmaster documentation for error codes like OFR_999.
Escalate if Needed: If initial support isn't helpful, request escalation to a deliverability specialist.
Summary of resolution
When facing unclassified soft bounces from Orange.fr in Klaviyo, the solution almost always lies in identifying and addressing the underlying IP reputation or connection limit issues, not content. While Klaviyo might classify them generically, a closer look at the actual bounce message often reveals a greeting failed error with an OFR_999 code, indicating a temporary block on the sending IP.
The responsibility for resolving these issues largely falls on your ESP, especially when using a shared IP pool. They are best equipped to manage IP reputation, adjust sending rates, and engage directly with ISPs like Orange.fr. Your role is to provide them with precise diagnostic information and advocate for a technical solution, ensuring they don't dismiss the problem as a content issue.
By understanding the technical nature of these bounces and pushing for the right level of support from your ESP, you can effectively resolve these deliverability challenges and maintain a healthy sending reputation. Always prioritize getting the raw bounce data to make informed decisions and ensure your email campaigns reach their destination.
Views from the trenches
Best practices
Always ask your ESP for the actual, raw SMTP bounce message, not just their categorized version. This provides the most precise diagnostic information.
Reference Orange.fr's official postmaster documentation for error codes like OFR_999 to support your claims when communicating with your ESP.
Ensure your domain has proper email authentication (DKIM, SPF, DMARC) set up, especially your own custom DKIM domain to help with reputation.
If on a shared IP, understand that the ESP (Klaviyo) is responsible for managing the IP's overall reputation and handling blocklist issues.
Common pitfalls
Misinterpreting "unclassified" as a content issue and wasting time on template changes or keyword removal like 'FREE'.
Attempting to contact Orange.fr directly about shared IP issues; this is typically the ESP's responsibility and will be unproductive.
Not escalating beyond initial support tiers when they fail to understand the technical nature of connection-level bounces.
Assuming all soft bounces are temporary and will resolve themselves without deeper investigation, leading to prolonged deliverability issues.
Expert tips
A "greeting failed" bounce indicates a problem at the very start of the SMTP conversation, before email content is parsed or evaluated.
For IP-based blocks, the solution often involves the ESP's deliverability team working to either delist the IP or adjust sending practices.
If Orange.fr is consistently rejecting mail with OFR_999, it likely points to a sustained reputation problem with the sending IP.
Having someone on your team who understands SMTP manually can quickly diagnose these complex bounce messages.
Marketer view
Marketer from Email Geeks says they might get clues about unclassified soft bounces if a pattern emerges for a specific ISP, suggesting they could approach that ISP for assistance.
2024-12-18 - Email Geeks
Expert view
wise_laura from Email Geeks says that ESPs can definitely see the exact bounce message in their logs and customers should ask for it to clarify what is happening.
Klaviyo can be a frustrating experience. Unlike a hard bounce, which indicates a permanent delivery failure, a soft bounce is typically temporary, often due to a full inbox or a server issue. However, when these bounces are unclassified, it means the email service provider (ESP) like Klaviyo cannot immediately pinpoint the exact reason for the bounce. This lack of specific information makes troubleshooting particularly challenging, leaving you without clear actionable insights.
Orange.fr within your Klaviyo account and outlines actionable strategies to diagnose and resolve them effectively. Understanding the true nature of these bounces is crucial for maintaining your email deliverability and ensuring your messages reach their intended recipients.
