Laposte.net SMTP Error Codes
Master French email delivery with our guide to Laposte.net SMTP errors. Understand LPN error codes, connection limits, and France's unique email requirements.
🇫🇷 About Laposte.net
Platform Overview
- • France's first and largest free webmail provider
- • Created in August 2000 by La Poste (French postal service)
- • Originally offered free email without needing Internet subscription
- • Millions of active @laposte.net accounts
- • Uses Vade (ex-Vade Secure) for spam filtering
Unique Features
- • Only French ISP with official BIMI support
- • VMC certificate not mandatory for BIMI
- • Partners with Signal Spam for FBL
- • Strict sender validation requirements
📊 Understanding LPN Error Codes
Laposte.net uses a unique error code system with the format LPNXXX_XXX. Each SMTP error message ends with a Laposte.net Error Code that has a specific meaning:
- LPN027_503 - Service temporarily refused
- LPN007_405 - Sender configuration issue
- LPN007_416 - Invalid recipient address
- LPN007_510 - Service refused (content/policy)
- LPN007_517 - DMARC policy rejection
Laposte.net SMTP Error Codes Explained
450 4.7.1
LPN027_503Laposte temporarily refused the connection after seeing too many errors or complaints.
LPN027_503 is Laposte’s generic throttle when reputation drops. It normally clears after a few hours if you slow delivery and clean your list.
How to Fix:
- ✓Reduce concurrent SMTP connections to no more than two per IP.
- ✓Respect Laposte’s limit of ~100 messages per connection.
- ✓Pause unengaged French recipients and remove obvious spam traps.
- ✓Check the Signal Spam feedback loop for complaint spikes.
450 4.1.8
LPN007_405Laposte rejected the sender address because it cannot receive mail.
Laposte requires functional reply-to addresses. Using no-reply mailboxes that bounce inbound mail results in LPN007_405.
How to Fix:
- ✓Ensure every From or Reply-To address accepts mail and is monitored.
- ✓Publish MX records for all sending domains.
- ✓Avoid auto-deleting replies; route them to a monitored mailbox instead.
- ✓If you need a no-reply address, add an alternate support contact in the footer.
450 4.1.7
LPN007_411Laposte could not resolve the MX records for the sender domain.
Laposte expects domains that send mail to also receive mail. Missing or incorrect MX records trigger LPN007_411.
How to Fix:
- ✓Publish MX records for the sender domain—even if you only receive mail on a subdomain.
- ✓Check for DNS typos or expired registrar settings.
- ✓Use monitoring to alert you when MX records change or disappear.
- ✓Fallback to a domain with verified MX records while remediation is underway.
450 4.2.1
The recipient’s Laposte mailbox is temporarily disabled or inactive.
Dormant mailboxes are common on older Laposte accounts. Treat the bounce as soft unless it occurs repeatedly over several weeks.
How to Fix:
- ✓Retry in subsequent campaigns before suppressing the address.
- ✓Run a win-back campaign targeting Laposte recipients who have not opened recently.
- ✓Flag the contact for sales or customer success outreach if the relationship is strategic.
- ✓Stop after 3–4 consecutive failures to avoid reputation damage.
450 4.7.0
LPN007_510Laposte refused the message because of temporary policy or content checks.
LPN007_510 is a soft block triggered by content heuristics or bursts of suspicious traffic. It often precedes harder policy bounces.
How to Fix:
- ✓Review subject lines, link domains, and attachments for spam traits.
- ✓Ensure authentication (SPF, DKIM, DMARC) passes for the sending domain.
- ✓Throttle bursty campaigns so Laposte can scan the stream gradually.
- ✓Check that localisation (FR language, legal footer) matches French law.
451 4.7.1
LPN007_512Laposte temporarily blocked the IP because of suspected spam behaviour.
This code signals elevated complaint rates, traps, or content Laposte finds risky. Without adjustments it can escalate to permanent blocks.
How to Fix:
- ✓Reduce sending speed and prioritise highly engaged French subscribers.
- ✓Remove addresses that hard bounced or never opened in the past six months.
- ✓Verify that no compromised accounts are injecting mail into your system.
- ✓Monitor Signal Spam and other FBL feeds for indicators of abuse.
550 5.1.1
LPN007_416Laposte confirmed the recipient mailbox does not exist.
Invalid Laposte addresses should be removed immediately. Continued retries quickly degrade the sender score for French ISPs.
How to Fix:
- ✓Delete the address after the first bounce and do not retry automatically.
- ✓Require confirmed opt-in for French recipients to avoid typos.
- ✓Sync suppression lists across ESPs so retired contacts stay retired.
- ✓If the address is business critical, ask the recipient to verify spelling or forwarding rules.
552 5.2.2
The Laposte recipient inbox is full and cannot accept additional mail.
Treat this as a soft bounce. Laposte recipients with small storage tiers fill up quickly, especially on older free accounts.
How to Fix:
- ✓Retry a few times over the course of several days.
- ✓Suppress chronically over-quota addresses to protect reputation.
- ✓Encourage recipients (where appropriate) to clear space or upgrade their mailbox.
- ✓Route critical notifications through alternative channels when possible.
550 5.7.1
LPN007_517Laposte rejected the message because DMARC alignment failed under a reject policy.
Laposte strictly enforces DMARC. Messages that fail alignment with a p=reject policy are blocked outright to protect subscribers.
How to Fix:
- ✓Ensure SPF or DKIM (preferably both) pass and align with the visible From domain.
- ✓Review DMARC aggregate reports to identify misaligned vendors or streams.
- ✓Provide subdomain-specific authentication when different teams send mail.
- ✓Temporarily relax DMARC to p=quarantine while you diagnose alignment gaps.
550 5.7.1
LPN007_518Laposte blocked the message because content or URLs violate local policy.
LPN007_518 is typically triggered by phishing-style copy, URL shorteners, or missing legal disclosures required by French law.
How to Fix:
- ✓Localise legal footers (mentions légales) and unsubscribe wording for the French market.
- ✓Avoid URL shorteners; use branded, HTTPS links that resolve quickly.
- ✓Remove aggressive promotional language that may resemble spam.
- ✓If false positive, share sample content and remediation steps with Laposte support.
Laposte.net Best Practices
Connection Limits
- •Maximum 2 concurrent SMTP connections per IP
- •Up to 100 messages per connection
- •Use single MX server: smtpz4.laposte.net
- •Implement proper connection pooling
Authentication
- •SPF, DKIM, and DMARC are required
- •BIMI supported (VMC not mandatory)
- •Only French provider with official BIMI support
- •Strict DMARC enforcement
French Compliance
- •Follow French anti-spam laws (LCEN)
- •Provide clear unsubscribe in French
- •Respect opt-in requirements
- •Include sender identification
List Management
- •Access feedback loops via Signal Spam
- •Available through Validity Universal FBL
- •Monitor aggregated complaint data
- •Remove complainers promptly
Technical Configuration
Laposte.net Connection Settings
MX: smtpz4.laposte.net
max_concurrent_connections = 2
max_messages_per_connection = 100
SPF: Required
DKIM: Required
DMARC: Required (strictly enforced)
BIMI: Supported (VMC optional)
Complaint Feedback Loops
Laposte.net partners with Signal Spam and Validity to provide comprehensive feedback loops. Some monitoring tools like Postmastery integrate data from the aggregated FBL through their partnership with Signal Spam.
📈 Aggregated FBL (CSV)
Daily complaint volumes by IP address, available to:
- • Signal Spam members
- • Validity Universal FBL subscribers (free)
- • CSV format with daily aggregates
📧 ARF Feedback Loop
Individual complaint reports in ARF format:
- • Signal Spam members
- • Validity FBL ($18+ per year)
- • Real-time ARF reports
French Email Requirements
📜 Legal Compliance (LCEN)
French law requires:
- Clear sender identification in every email
- Easy unsubscribe mechanism (in French)
- Explicit consent for marketing emails
- Data protection compliance (RGPD/GDPR)
🌐 Language Considerations
- Include French language options in emails
- Error messages are bilingual (French/English)
- Support communications should be in French
- Consider French timezone for sending times
Laposte.net Resources
📞 Contacting Laposte.net Support
When contacting Laposte.net's efficient abuse desk, include:
- ✓Date and time of occurrence
- ✓Sending IP address(es)
- ✓Sending hostname(s)
- ✓Sending domain
- ✓Complete SMTP error code with LPN reference
Need Help with French Email Delivery?
Navigating French email requirements and Laposte.net's unique LPN error system can be complex. Let us help you optimize your email delivery to French recipients.